Answer:
Kr < Ar < Ne < N (N is fastest and Kr is slowest)
Explanation:
According to graham law of diffusion, rate of diffusion of a gas is inversely proportional to the square root of molar mass of the gas.
[tex]R\propto \frac{1}{\sqrt{M}}[/tex]
Where R is rate of diffusion and M is molar mass
Molar masses of given gases are - Ar(40 g/mol), Ne(20 g/mol), N(14 g/mol) and Kr(84 g/mol)
So molar mass order : Kr > Ar > Ne > N
Hence rate of diffusion order: Kr < Ar < Ne < N (N is fastest and Kr is slowest)
The perspective formula of threonine, an amino acid with two asymmetric centers, is provided below. perspective formula of threonine add either an h, oh, or nh2 group to complete the fischer projection for threonine.
Why must you carry out the oxidation of cu with hno3 in a fume hood?
Which substance is the reducing agent in this reaction? 16h++2cr2o72−+c2h5oh→4cr3++11h2o+2co2?
Answer is: the reducing agent is C₂H₅OH.
Balanced chemical reaction:
16H⁺ + 2Cr₂O₇²⁻ + C₂H₅OH → 4Cr³⁺ + 11H₂O + 2CO₂.
Oxidation half reaction: Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O/ ×2.
2Cr₂O₇²⁻ + 28H⁺ + 12e⁻ → 4Cr³⁺ + 14H₂O.
Reduction half reaction: C₂H₅OH + 3H₂O → 2CO₂ + 12H⁺ + 12e⁻.
Net reaction: 2Cr₂O₇²⁻ + 28H⁺ + C₂H₅OH + 3H₂O → 4Cr³⁺ + 14H₂O + 2CO₂ + 12H⁺.
Reducing agent is element or compound who loose electrons in chemical reaction. Ethanol (C₂H₅OH) lost electrons and it is oxidized to carbon dioxide (CO₂).
The reducing agent in the reaction is [tex]\boxed{\text{C}_{2}\text{H}_{5}\text{OH}}[/tex].
Further Explanation:
Redox reaction:
Redox is a term that is used collectively for the reduction-oxidation reaction. It is a type of chemical reaction in which the oxidation states of atoms are changed. In this reaction, both reduction and oxidation are carried out simultaneously. Such reactions are characterized by the transfer of electrons between the species involved in the reaction.
The process of gain of electrons or the decrease in the oxidation state of the atom is called reduction while that of loss of electrons or the increase in the oxidation number is known as oxidation. In redox reactions, one species lose electrons and the other species gain electrons. The species that lose electrons and itself gets oxidized is called as a reductant or reducing agent. The species that gains electrons and gets reduced is known as oxidant or oxidizing agent. The presence of redox pair or redox couple is a must for the redox reaction.
The general representation of a redox reaction is,
[tex]\text{X}+\text{Y}\rightarrow\text{X}^{+}+\text{Y}^{-}[/tex]
The oxidation half-reaction can be written as:
[tex]\text{X}\rightarrow\text{X}^{+}+e^{-}[/tex]
The reduction half-reaction can be written as:
[tex]\text{Y}+e^{-}\rightarrow\text{Y}^{-}[/tex]
Here, X is getting oxidized and its oxidation state changes from to +1 whereas B is getting reduced and its oxidation state changes from 0 to -1. Hence, X acts as the reducing agent, whereas Y is an oxidizing agent.
Rules to calculate the oxidation states of elements:
1. The oxidation number of free element is always zero.
2. The oxidation number of oxygen is generally taken as -2, except for peroxides.
3. The oxidation state of hydrogen is normally taken as +1.
4. The sum of oxidation numbers of all the elements present in a neutral compound is zero.
5. The oxidation numbers of group 1 and group 2 elements are +1 and +2 respectively.
The oxidation state of O is -2.
The expression to calculate the oxidation number in [tex]\text{Cr}_{2}\text{O}_{7}^{2-}[/tex] is:
[tex]\left[2(\text{Oxidation state of Cr})+7(\text{oxidation state of O})\right]=-2[/tex] ...... (1)
Rearrange equation (1) for oxidation number of Cr
[tex]2(\text{Oxidation number of Cr})=\left[(-2)-7(\text{oxidation number of O})\right][/tex] …… (2)
Substitute -2 for oxidation state of O in equation (2).
[tex]\begin{aligned}\text{Oxidation state of Cr}&=\dfrac{[(-2)-7(-2)]}{2}\\&=\dfrac{[-2+14]}{2}\\&=+6\end{aligned}[/tex]
The charge on Cr is +3 so its oxidation state is also +3. The oxidation state of Cr changes from +6 to +3. This shows it decreases during the reaction and therefore Cr is an oxidizing agent.
The oxidation state of O is -2 and the oxidation state of H is +1.
The expression to calculate the oxidation in [tex]\text{C}_{2}\text{H}_{5}\text{OH}[/tex] is:
[tex]\left[2(\text{oxidation state of C})+1(oxidation state of O)+6(oxidation state of H)\right]=0[/tex] ...... (3)
Rearrange equation (3) for oxidation state of C
[tex]2(\text{oxidation state of C})=\left[-1(oxidation state of O)-6(oxidation state of H)\right][/tex] ...... (4)
Substitute -2 for oxidation state of O and +1 for oxidation state of H in equation (4).
[tex]\begin{aligned}\text{Oxidation state of C}&=\dfrac{[-1(-2)-6(+1)]}{2}\\&=\dfrac{[+2-6]}{2}\\&=-2\end{aligned}[/tex]
The oxidation state of O is -2.
The expression to calculate the oxidation state in [tex]\text{CO}_{2}[/tex] is:
[tex]\left[(\text{oxidation state of C})+2(oxidation state of O)\right]=0[/tex] ...... (5)
Rearrange equation (5) for oxidation state of C
[tex](\text{oxidation state of C})=\left[-2(oxidation state of O)\right][/tex] ...... (6)
Substitute -2 for oxidation state of O in equation (6).
[tex]\begin{aligned}\text{Oxidation state of C}&=[-2(-2)]\\&=+4\end{aligned}[/tex]
The oxidation state of C changes from -2 to +4. This shows it increases during the reaction and therefore [tex]\textbf{C}_{2}\textbf{H}_{5}\textbf{OH}[/tex] acts as a reducing agent.
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Answer details:
Grade: High School
Subject: Chemistry
Chapter: Redox reactions
Keywords: redox reaction, C2H5OH, Cr, C, CO2, Cr2O72-, oxidation, reduction, reductant, oxidant, reducing agent, oxidizing agent, electrons, redox pair, redox couple, oxidation state, oxidized, reduced, simultaneously.
Why are covalent bonds between hydrogen and nitrogen or oxygen polar? see section 2.1 ( page 57) ?
In a chemical reaction, water decomposes to form hydrogen and oxygen. Which term names the water? A. an element B. an atom C. a product D. a reactant
The term that name the water in a chemical reaction that water decomposes is.
reactant ( answer D)
Explanation
Reactant is a substance that take part in and undergoes change during a reaction. In other words reactant are consumed to form product.
water is reactant when it decomposes because it is consumed to form hydrogen and oxygen.
The decomposition of water is as below equation,
2H2O→ 2 H2 + O2
Mastering chemistry if the new ring is indeed pure platinum (density = 21.4 g/cm3), what is its mass?
In 1986 an electrical power plant in taylorsville, georgia, burned 8,376,726 tons of coal, a national record at that time. assuming that the coal was 80.7 % carbon by mass and that combustion was complete, calculate the number of tons of carbon dioxide produced by the plant during the year. if 71.0 % of the so2 could be removed by reaction with powdered calcium oxide, cao, via the reaction
297440787 tons of carbon dioxide is produced by the plant after a combustion reaction taking place.
How to calculate mass from combustion reaction?Reaction which takes place in presence of air is combustion reaction.When carbon burns in air it produces carbon dioxide .
C+O₂[tex]\rightarrow[/tex]CO₂
80.7% mass of carbon means 80.7/100×12=9.684 g
12 g C is present in 44 g carbon dioxide
∴9.684 g of C is present in 9.684×44/12=35.508 g
As 9.6854 g carbon/coal produces 35.508 g carbon dioxide ,
∴35.508×8376726=297440787 tonnes of carbon dioxide.
Combustion reactions are reactions which take place at high temperatures and are exothermic and produce products which are oxidized.In combustion reactions ,chemical equilibrium is difficult to achieve. There are 3 types of combustion:
1) rapid combustion
2) explosive combustion
3) spontaneous combustion
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Insulin, adrenaline, and estrogen are examples of
In the given question, Insulin, adrenaline, and estrogen are examples of hormones. Each hormone has a specific function and plays an important role in maintaining homeostasis in the body.
Insulin is a hormone made up of 51 amino acids and is released by the beta cells of pancreas. It helps in regulating blood glucose level.
Adrenaline is also known as epinephrine. It is produced by the adrenal glands and is involved in the body's "fight or flight" response to stress.
Estrogen is a female sex hormone produced by the ovaries and is involved in the development of female secondary sexual characteristics, such as breast development and the menstrual cycle.
Therefore, examples of hormones are insulin, adrenaline, and estrogen, which are chemical messengers that regulate many physiological processes in the body.
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Based on the answers to parts (a)-(c), explain why cinnamaldehyde is not miscible with water. incorporate relevant intermolecular forces in your answer.
The combination of a single polar group and dominant non-polar regions prevents effective hydrogen bonding with water, leading to the immiscibility of cinnamaldehyde in water.
**Structure:**
O
|
C=CH-CH=CH-CH2-CH2-CH3
|
H
**Analysis:**
a) **Non-polar regions:**
* **Double bonds:** The double bonds (C=C) have evenly distributed electron density, making them non-polar. Circle both double bonds.
* **Alkyl chains:** The aliphatic chains (CH2-CH2-CH3) also have similar electron densities across their C-H bonds, making them non-polar. Circle both alkyl chains.
b) **Polar region:**
* **Carbonyl group (C=O):** The carbonyl group has a significant dipole moment due to the electronegativity difference between oxygen and carbon. This creates a partial positive charge on the carbon and a partial negative charge on the oxygen. Circle the carbonyl group (C=O).
c) **Water's preferred intermolecular force:**
* **Hydrogen bonding:** Water molecules are highly polar due to their lone pairs and O-H bonds, enabling strong hydrogen bonding with other polar molecules.
d) **Cinnamaldehyde's immiscibility with water:**
* Although the carbonyl group is polar, its interaction with water is significantly weakened by the extensive non-polar regions (double bonds and alkyl chains) dominating the molecule.
* These non-polar regions prefer London dispersion forces (weak attractive forces between all molecules due to temporary fluctuations in electron density) over the stronger hydrogen bonding with water.
* The weak London dispersion forces cannot overcome the stronger intermolecular hydrogen bonding network of water, resulting in immiscibility.
Therefore, the combination of a single polar group and dominant non-polar regions prevents effective hydrogen bonding with water, leading to the immiscibility of cinnamaldehyde in water.
The probable question may be:
1. Re-draw the chemical structure of cinnamaldehyde and use it to answer the following solubility-based questions:
a) Circle and label all regions of the molecule that exhibit non-polar behavior.
b) Circle and label the region of the molecule that exhibits polar behavior.
c) Water prefers to interact with solute molecules with what type of intermolecular force (choose one answer): hydrogen bonding, dipole- induced dipole, or induced dipole-induced dipole (London dispersion)?
d) Based on the answers to parts (a)-(c), explain why cinnamaldehyde is NOT miscible with water. Incorporate relevant intermolecular forces in your answer.
Two liquids – one polar, one nonpolar – have the same molar mass. which one has the higher boiling point?
One cup of fresh orange juice contains 124 mg of ascorbic acid (vitamin c, c6h8o6). given that one cup = 236.6 ml, calculate the molarity of vitamin c in organic juice.
Answer : The molarity of vitamin c in organic juice is, [tex]2.97\times 10^{-3}mole/L[/tex]
Solution : Given,
Mass of ascorbic acid (solute) = 124 mg = 0.124 g [tex](1mg=0.001g)[/tex]
Volume of juice = 236.6 ml
Molar mass of ascorbic acid = 176.12 g/mole
Formula used :
[tex]Molarity=\frac{\text{Moles of solute}\times 1000}{\text{Molar mass of solute}\times \text{volume of solution}}[/tex]
Now put all the given values in this formula, we get the molarity of vitamin c in organic juice.
[tex]Molarity=\frac{0.124g\times 1000}{176.12g/mole\times 236.6ml}=2.97\times 10^{-3}mole/L[/tex]
Therefore, the molarity of vitamin c in organic juice is, [tex]2.97\times 10^{-3}mole/L[/tex]
Final answer:
The molarity of vitamin C in orange juice, where one cup contains 124 mg of ascorbic acid and is equal to 236.6 mL, is approximately 0.00297 M.
Explanation:
To calculate the molarity of vitamin C in orange juice, we can use the formula for molarity:
Molarity = moles of solute / liters of solution
First, we need to find the number of moles of ascorbic acid in one cup of orange juice.
1 cup of orange juice contains 124 mg of ascorbic acid. Since the molar mass of ascorbic acid, C6H8O6, is 176.12 g/mol, we convert the mass from mg to grams and then to moles:
124 mg * (1 g / 1000 mg) * (1 mol / 176.12 g) = 0.000704 mol
Next, we convert the volume from milliliters to liters:
236.6 mL * (1 L / 1000 mL) = 0.2366 L
Now, we can calculate the molarity:
Molarity = 0.000704 mol / 0.2366 L ≈ 0.00297 M
Thus, the molarity of vitamin C in the orange juice is approximately 0.00297 M.
Complete and balance the molecular equation, including phases, for the reaction of aqueous iron(III) nitrate, Fe(NO3)3 and aqueous lithium hydroxide, LiOH.
The Complete balanced equation for the reaction of Aqueous iron (iii) nitrate, Fe(NO3)3 and aqueous lithium hydroxide, LiOH, is given by;
Fe(NO₃)₃(aq) + 3LiOH(aq) → 3LiNO₃(aq) + Fe(OH)₃(s)
Further Explanation:Chemical equations Chemical equations are equations showing reactions between reactants to form products. Chemical equations show the reactants or starting substances and products or substances formed during the reaction.Law of conservation of mass The law of conservation requires that when writing chemical equations, the mass of the reactants should be equal; to the mass of the products.This is done by making sure the number of atoms of each element involved in the chemical equation is equal on both sides of the equation.To ensure the law of conservation in chemical equations is observed we balance chemical equations.Balancing chemical equation:Balancing chemical equations is a try and error method that ensures the number of atoms in the side of the reactants is equal to the number of atoms in the side of products.Balancing chemical equations may also require inclusion of state symbols which shows the state of each compound or element involved in the chemical reactions.For example; the equation; Fe(NO₃)₃(aq) + 3LiOH(aq) → 3LiNO₃(aq) + Fe(OH)₃(s), is balanced as there are equal number of atoms of any given element on both sides; A single atom of Fe, six oxygen atom, 3 nitrogen atoms and 3 lithium atoms on both side of the equation.
Keywords: Chemical equations, balancing of chemical equations
Learn more about:Chemical equations: brainly.com/question/5297242Balancing of chemical equations: brainly.com/question/5297242Law of conservation of mass: brainly.com/question/5297242Level: high school
Subject: Chemistry
Topic: Chemical equations
Sub-topic: Balancing chemical equations
The balanced chemical equation between aqueous iron(III)nitrate and aqueous lithium hydroxide is Fe(NO₃)₃[tex]_(aq)[/tex] + 3 LiOH [tex]_(aq)[/tex][tex]\rightarrow[/tex] 3 LiNO₂ [tex]_(aq)[/tex] +Fe(OH)₃[tex]_(s)[/tex].
What is a chemical equation?Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.
A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .
The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.
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calculate the number of Kilojoules to warm 125 g of iron from 23.5 C to 78.0 C
List the subatomic particles in terms of their mass from least to greatest.
If a room is 212 m long how many hm is it
The room is approximately 0.0212 hectometers long.
To convert the length of the room from meters to hectometers, we need to know that 1 hectometer (hm) is equal to 100 meters (m). Therefore, to convert meters to hectometers, we divide the length in meters by 100.
Given that the room is 212 meters long, we perform the following calculation:
[tex]\[ \text{Length in hectometers} = \frac{\text{Length in meters}}{100} \][/tex]
[tex]\[ \text{Length in hectometers} = \frac{212 \text{ m}}{100} \][/tex]
[tex]\[ \text{Length in hectometers} = 2.12 \text{ hm} \][/tex]
However, to express this length in a more standard form, we can write 2.12 hectometers as 212/10000 hectometers, which simplifies to 212 hm divided by 100, or 2.12 hm. To be more precise, we can express this as a decimal:
[tex]\[ \text{Length in hectometers} = 0.0212 \text{ hm} \][/tex]
Thus, the room is approximately 0.0212 hectometers long.
Observation and assessment are most effective when
A. tools are appropriate for the children in your setting and meet professional requirements for quality.
B. the state has selected them as an appropriate tool for you to use.
C. parents select the tools you use.
D. assessments are formal and gather focused information.
Answer:
A. Tools are appropriate for the children in your setting and meet professional requirements for quality.
Explanation:
This is correct! C::
Remember to use the proper number of significant figures and leading zeros in all calculations. A sample has a mass of 35.4 g and a volume of 36.82 mL. What is the density of the sample?
1.04011 g/mL
1.04 g/mL
0.96143 g/mL
0.961g/mL
Answer : The correct option is, 0.961 g/ml
Solution : Given,
Mass of sample = 35.4 g
Volume of sample = 36.82 ml
Formula used :
[tex]\text{Density of sample}=\frac{\text{Mass of sample}}{\text{Volume of sample}}[/tex]
Now put all the given values in this formula, we get the density of the sample.
[tex]\text{Density of sample}=\frac{35.4g}{36.82ml}=0.961g/ml[/tex]
Therefore, the density of the sample is, 0.961 g/ml
Answer:
The correct option is, 0.961 g/ml
Explanation:
As a scuba diver descends under water, the pressure increases. at a total air pressure of 2.85 atm and a temperature of 25.0 ∘c, what is the solubility of n2 in a diver's blood? [use the value of the henry's law constant k calculated in part a, 6.26×10−4mol/(l⋅atm).] assume that the composition of the air in the tank is the same as on land and that all of the dissolved nitrogen remains in the blood. express your answer with the appropriate units.
The solubility of nitrogen in a diver's blood at a pressure of 2.85 atm and a temperature of 25.0 ∘c is 1.78 x 10^-3 moles per litre, according to Henry's law.
Explanation:In this context, we will use Henry's law to calculate the solubility of N2 in a diver's blood. According to Henry's law, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. The equation is: C = P * k, where C is the solubility of the gas in the liquid, P is the partial pressure of the gas, and k is Henry's law constant.
In the given situation, the total pressure is 2.85 atm (which is the sum of the partial pressures of all gases), and the value of Henry's law constant (k) for N2 is 6.26×10−4mol/(l⋅atm). So, the solubility of nitrogen can be calculated by multiplying the pressure by Henry's law constant: C = 2.85 atm * 6.26×10−4mol/(l⋅atm) = 1.78 x 10^-3 mol/L.
Therefore, at a pressure of 2.85 atm and a temperature of 25.0 ∘c, the solubility of nitrogen in a diver's blood is 1.78 x 10^-3 moles per litre.
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Element x reacts with oxygen to produce x2o3 in an experiment it is found that 1.0000 g of x produces 1.1xxx g of x2o3 what is the molar mass of x?
The molar mass of element X is determined in g/mol by taking into account the mole ratio in the X₂O₃ compound. The mass of X (1.0000 g) is first divided by the moles of X, which is two-thirds of the moles of Oxygen, calculated by dividing the mass of Oxygen in X₂O₃ by its molar mass.
Explanation:To calculate the molar mass of element X, the mole ratio in the X₂O₃compound needs to be considered. This mole ratio suggests that for every 1 mole of X, 1.5 moles of Oxygen is used given that from the formula of X₂O₃hat would be 2 moles of X for every 3 moles of oxygen (2:3).
The mass of Oxygen in the compound can be calculated by subtracting the mass of X from the total compound weight. Given that 1.1xxx grams of X₂O₃ was obtained from 1.0000 grams of X, the mass of Oxygen in the compound would be 1.1xxx g - 1.0000 g giving a mass of Oxygen in the compound as 0.1xxx grams.
We know that the molar mass of Oxygen (O) is 16.00 g/mol. So, the number of moles of Oxygen in the compound can be calculated as (0.1xxx g)/(16.00 g/mol) which gives the number of moles for Oxygen. Given the mole ratio from the X₂O₃ formula, the number of moles of X will be two-thirds of the moles of Oxygen.
Finally, the molar mass of X can be calculated by dividing the mass of X (1.0000 g) by the number of moles of X calculated. This will give the answer for the molar mass of X in g/mol.
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(4 ten thousands 7 tens) × 10
Provide three different examples of how minerals can form on earth
Convert 870 kg to pounds
A student titrates an unknown amount of potassium hydrogen phthalate (khc8h4o4, abbreviated khp) with 20.46 ml of 0.1000 m naoh solution. khp has one acidic hydrogen. what mass (in grams) of khp was titrated by the sodium hydroxide solution?
Water boils at 373 K. The molar enthalpy of vaporization for water is 40.7 kJ/mol. If one mole of water is at 373 K when it starts to boil, its temperature when it all has boiled will be ____________________. a. 273 K c. 373 K b. 343 K d. 413 K
Answer: c. 373 K
Explanation:
What mass of ammonium thiocyanate must be used if it is to react completely with 6.5 g barium hydroxide octahydrate?
The mass of a mouse is around 22 grams (0.022 kg). What is the weight of a mouse on the Moon?
Answer: The weight of the mouse on the Moon is 0.036 N
Explanation:
Weight is defined as the force exerted by the body on any surface. It is also defined as the product of mass of the body multiplied by the acceleration due to gravity.
Mathematically,
[tex]W=mg[/tex]
where,
W = weight of the mouse
m = mass of the mouse = [tex]22g=0.022kg[/tex]
g = acceleration due to gravity on moon = [tex]1.625m/s^2[/tex]
Putting values in above equation, we get:
[tex]W=0.022kg\times 1.625 m/s^2=0.036N[/tex]
Hence, the weight of the mouse on the Moon is 0.036 N
Which characteristic best explains the difference in melting behavior of covalent substances and ionic substances?
Answer:
C
Explanation:
A 1.248 g sample of limestone rock is pulverized and then treated with 30.00 ml of 1.035 m hcl solution. the excess acid then requires 11.56 ml of 1.010 m naoh for neutralization. part a calculate the percent by mass of calcium carbonate in the rock, assuming that it is the only substance reacting with the hcl solution.
The percentage by mass of calcium carbonate present in rock is [tex]\boxed{{\mathbf{77}}{\mathbf{.62 \% }}}[/tex].
Further Explanation:
First, we have to find the excess number of moles of HCl acid that are neutralized by NaOH.
The number of moles of NaOH in 11.56 ml of 1.010 M NaOH solution is calculated as follows:
[tex]\begin{aligned}{\text{Number of moles of NaOH}}\left({{\text{mol}}}\right)&={\text{Concentration }}\left( {{\text{mol/L}}}\right) \times{\text{Volume }}\left({\text{L}} \right)\\&= 1.010{\text{ mol/L}}\left({11.56{\text{ ml}}\times \frac{{1{\text{ L}}}}{{1000{\text{ml}}}}}\right)\\&=0.011676{\text{ mol}}\\\end{aligned}[/tex]
The balanced chemical reaction of NaOH and HCl is as follows:
[tex]{\text{NaOH}}\left({aq}\right)+{\text{HCl}}\left({aq}\right)\to{\text{NaCl}}\left({aq} \right) +{{\text{H}}_{\text{2}}}{\text{O}}\left( l \right)[/tex]
Since NaOH and HCl are reacted in 1:1 ratio, therefore, the excess number of moles of HCl are equal to number of moles of NaOH that is 0.011676 mol.
Now, we have to find how many moles of HCl initially reacted with limestone.
The initial number of moles of HCl in 30.00 ml of 1.035 M HCl solution is calculated as follows:
[tex]\begin{aligned}{\text{Number of moles of HCl}}\left( {{\text{mol}}}\right)&={\text{Concentration }}\left( {{\text{mol/L}}}\right) \times {\text{Volume }}\left({\text{L}} \right)\\&= 1.035{\text{ mol/L}} \times \left( {30.00{\text{ ml}}\times \frac{{1{\text{ L}}}}{{1000\,{\text{ml}}}}}\right)\\&=0.03105{\text{ mol}}\\\end{aligned}[/tex]
Therefore, the number of moles of HCl initially reacted with limestone is calculated as follows:
[tex]\begin{aligned}{\text{Number of moles of HCl reacted with CaC}}{{\text{O}}_3}&=\left({0.03105{\text{ mol}} - 0.011676{\text{ mol}}}\right)\\&={\text{0}}{\text{.019374 mol of HCl}}\\\end{aligned}[/tex]
Therefore, the number of moles of HCl initially reacted with limestone is 0.019374 mol.
The balanced chemical equation for the reaction of limestone [tex]\left( {{\text{CaC}}{{\text{O}}_{\text{3}}}}\right)[/tex] with HCl is as follows:
[tex]{\text{CaC}}{{\text{O}}_3}\left( s \right) + 2{\text{HCl}}\left( {aq} \right)\to{\text{C}}{{\text{O}}_{\text{2}}}\left( g \right) + {{\text{H}}_{\text{2}}}{\text{O}}\left( l \right) + {\text{CaC}}{{\text{l}}_2}\left( {aq} \right)[/tex]
The balanced chemical equation shows that 1 mole of [tex]{\text{CaC}}{{\text{O}}_3}[/tex] reacted with 2 moles of HCl to neutralize the reaction completely, therefore, the number of moles of [tex]{\text{CaC}}{{\text{O}}_3}[/tex] neutralized by 0.019374 mol of HCl are calculated as follows:
[tex]\begin{aligned}{\text{Amount of CaC}}{{\text{O}}_3}\left( {{\text{mol}}}\right)&= \left( {{\text{0}}{\text{.019374 mol of HCl}}}\right)\left({\frac{{1{\text{ mol CaC}}{{\text{O}}_3}}}{{{\text{2 mol HCl}}}}}\right)\\&=0.009687{\text{ mol CaC}}{{\text{O}}_3}\\\end{aligned}[/tex]
The molar mass of [tex]{\text{CaC}}{{\text{O}}_3}[/tex] is 100.0 g/mol.
Mass of 0.009687 mol of [tex]{\text{CaC}}{{\text{O}}_3}[/tex] is calculated as follows:
[tex]\begin{aligned}{\text{Mass}}\left( {\text{g}}\right)&={\text{Number of moles}} \times{\text{Molarmass}}\left({{\text{g/mol}}}\right)\\&=0.009687{\text{mol}}\times{\text{100}}{\text{.0 g/mol}}\\&=0.9687{\text{g}}\\\end{aligned}[/tex]
The percentage by mass can be calculated as follows:
[tex]\begin{aligned}{\text{Percent by mass}}\left( \%\right)&=\frac{{{\text{Mass of CaC}}{{\text{O}}_3}}}{{{\text{Mass of lime stone}}}}\times 100\\&=\frac{{0.9687{\text{ g}}}}{{1.248{\text{ g}}}}\times 100\\&=77.62{\text{ }}\%\\\end{aligned}[/tex]
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Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Mole concept
Keywords: Percentage by mass, calcium carbonate in rock, number of moles of HCl, excess number of moles, CaCO3, balance chemical equation, limestone.
Final answer:
To calculate the percent by mass of calcium carbonate in the limestone, we calculate the moles of HCl that reacted with the limestone, subtract the moles neutralized by NaOH, convert this to grams of CaCO₃, and divide by the sample mass.
Explanation:
To calculate the percent by mass of calcium carbonate in the limestone rock, we need to find out how much of the HCl was used to react with the calcium carbonate and not neutralized by NaOH, and then convert this amount to grams of CaCO3.
We start by calculating the number of moles of NaOH that reacted with the excess HCl:
Number of moles of NaOH = Volume (L) × Molarity (M)
Number of moles of NaOH = 0.01156 L × 1.010 M = 0.0116776 mol
Since the reaction between NaOH and HCl is 1:1, the moles of HCl that were neutralized by NaOH are also 0.0116776 mol.
Now we can calculate the moles of HCl that reacted with the CaCO3:
Total moles of HCl initially = Volume (L) × Molarity (M)
Total moles of HCl = 0.03000 L × 1.035 M = 0.03105 mol
Moles of HCl that reacted with CaCO₃ = Total moles of HCl - Moles of HCl neutralized by NaOH
Moles of HCl that reacted with CaCO₃ = 0.03105 mol - 0.0116776 mol = 0.0193724 mol
The reaction between CaCO₃ and HCl is also 1:1:
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
Moles of CaCO₃ = Moles of HCl that reacted with CaCO₃ = 0.0193724 mol
To find the mass of CaCO₃ we multiply the moles of CaCO₃ by the molar mass of CaCO₃ (100.09 g/mol):
Mass of CaCO₃ = Moles of CaCO₃ × Molar Mass of CaCO₃
Mass of CaCO₃ = 0.0193724 mol × 100.09 g/mol = 1.93936 g
Finally, we calculate the percent by mass of CaCO₃ in the rock:
Percent by mass of CaCO₃ = (Mass of CaCO₃ / Mass of Rock Sample) × 100%
Percent by mass of CaCO₃ = (1.93936 g / 1.248 g) × 100% = 155.413%
However, a percent mass over 100% indicates an error in the calculation as it's not possible to have more calcium carbonate than the total mass of the rock. It likely means that we must take into account other substances in the limestone that might react with HCl or a calculation error.
A substance undergoes a change. Which of the following indicates that the change was a chemical change?
a. The substance changed shape.
b. New molecules formed.
c.The substance froze.
d. The substance changed size.
Answer:
The answer is B.
Explanation:
Which of these is the lowest subgroup? kingdom, order, genus, or species.
Answer:
Species
Explanation:
The acronym, DKPCOFGS; Gives you an explanation of the subgroups highest - lowest.
Did
King
Phil
Come
Over
For
Good
Spagettii
Spagettii is species in the acronym
Enjoy your test :D
-Snooky