What is the mass of 3.00 moles of magnesium chloride, MgCl2? Express your answer with the appropriate units.

The enthalpy change for the thermite reaction when 8.00 mol of Al reacts is -6812 kJ.

The enthalpy change for the thermite reaction can be calculated using Hess's law. The overall reaction can be broken down into three steps, each with its own known enthalpy change values. The enthalpy change for the reaction is the sum of the enthalpy changes for each step.

In this case, the enthalpy change for the reaction is -851.5 kJ/mol of Fe₂O₃. To calculate the enthalpy change when 8.00 mol of Al reacts, you can multiply the enthalpy change by the number of moles of Al consumed, which is 8.00 mol. This gives a total enthalpy change of -851.5 kJ/mol x 8.00 mol = -6812 kJ.

Therefore, the enthalpy change for the thermite reaction when 8.00 mol of Al reacts is -6812 kJ.

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Substituting 6M NaOH for 6M NH3 in testing the reference solution would result in a more basic solution and a higher pH.

When testing a reference solution, if 6M NaOH is substituted for the 6M NH3, a different observation would be made. NH3 is a weak base, while NaOH is a strong base. In this case, the pH of the solution would change significantly since NaOH completely dissociates in water, producing a high concentration of hydroxide ions. On the other hand, NH3 only partially reacts with water, resulting in a lower concentration of hydroxide ions. Therefore, substituting NaOH for NH3 would result in a more basic solution and a higher pH.

Option A. Smaller atoms and stronger bonds.

Smaller the size of the atoms, less will be the distance between positive charge nucleus of one atom and electrons (negative charge) of other atom. This results in strong interaction between them.

Also, stronger bonds are difficult to break, making the minerals harder. Thus, small atoms and strong bonds in minerals makes then harder than the minerals with weak bonds or larger atoms.

Much of this frozen glaciers and ice caps, so we don't consider it usable freshwater.

This statement tells about the freshwater usage out of the whole water available on earth some are stored in the form of glaciers, ice caps, etc. Which cannot be used as freshwater.

Answer:

1. Aquifer

2. Deposition

3. recharge

4. water table

5. 97%

6. 1%

7. Fresh Water

8. Rain

9. underground

10. water contamination

Explanation:

Got a 100% on the quiz

To solve this, we must remember that the number of moles in each formula must a whole number.

So we are given two X’s:

X = 0.3

X = 0.39

We divide the two by the smallest X, so divide by 0.3:

X = 0.3 / 0.3 = 1

X = 0.39 / 0.3 = 1.3

However the second X is not a whole number yet, therefore multiply the two X’s by 3 to make them whole numbers:

X = 1 * 3 = 3

X = 1.3 * 3 = 4

So the X’s must be: X3 and X4 and based from the choices, the answer is:

X3Y and X4Y

The plausible sets of formulas for these two  compounds are:

A. X2Y and X3Y

B. XY3 and XY4

C. X3Y and X4Y

D. XY and X3Y

E. XY and X2Y

F. X2Y5 and X3Y5

G. X4Y2 and X3Y

I think the correct answers are A and F. and G:

If we look at the combining masses of X and Y in each of the two compounds, the first compound contains 0.25 g of X combined with 0.75 g of Y, therefore the ratio (by mass) of X to Y is 1 : 3. Whereas the second compound contains 0.33 g of X combined with 0.67 g of Y, therefore the ratio (by mass) of X to Y is 1 : 2.

Then, suppose prepared each of these two compounds, starting with the same fixed mass of element Y (I will choose 12 g of Y for an easy calculation) 

The first compound will then contain 4g of X and 12g of Y. Next the second compound will then contain 6g of X and 12g of Y. The ratio which combined the masses of X and the fixed mass (12 g) of Y = 4 : 6 or 2 : 3.

So, the ratio of Moles of X which combined with the fixed amount of Y in the two compounds is also 2 : 3. Then the two compounds given with the plausible formula must therefore contain the same ratio.

Grade:  9

Subject: Chemistry  

Chapter: compounds

Keywords: the generic elements X,  the generic elements Y,  two  compounds, XY, X3Y

13 kilojoules

Given:

A synthesis of ammonia in which the volume contracts from 7.4 l to 4.5 l at a constant external pressure of 44 atm.

Question:

Calculate the work in kilojoules done during the synthesis of ammonia. Express your answer using two significant figures.

The Process:

Let us calculate the change in volume and also convert units.

[tex]\boxed{ \ \Delta V = V_2 - V_1 \ }[/tex]

[tex]\boxed{ \ \Delta V = 4.5 - 7.4 \ }[/tex]

Therefore ΔV = - 2.9 L.

Work done during expansion and contraction at constant pressure.

[tex]\boxed{ \ W = p \ \Delta V \ }[/tex]

Let us find out the work done.

[tex]\boxed{ \ W = 4,457,200 \times -2.9 \times 10^{-3} \ }[/tex]

W = -12,925.88 joules

W = -13,000 joules to 2 significant figure.

Thus, the work in kilojoules done during the synthesis of ammonia is 13 kilojoules.

- - - - - - - - - -

Notes

- - - - - - - - - -

Notes:

Answer:

Answers are in the image.

Explanation:

In dehydration reaction of alcohols, alcohols lose water to generate alkene proceeds by heating the alcohols in the presence of a strong acid, such as sulfuric or phosphoric acid (HX), at high temperatures. The most substituted alkene are formed preferentially

The products and mechanism are in the images.

I hope it helps!

Answer:

A substance with precise melting and freezing point.

Explanation:

A pure substance is one that has a precise melting and freezing point

Like water, pure water boils at 100C while impure water will boil at a temperature less than that.

Impurity also affects the refractive index and specific gravity of a substance

The mass, in grams, of Ag is produced from reaction of 31.75 g of Cu is 107.9g

The mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure of the number of atoms or molecules in a bulk sample of matter.

A mole is defined as the amount of substance containing the same number of atoms, molecules, ions, etc. as the number of atoms in a sample of pure 12C weighing exactly 12 g.

Given,

Mass of Cu = 31.75g

Molar mass of Cu = 63.5 g/mol

Moles of Cu = 31.75 / 63.5

= 0.5 moles

From the reaction, 1 mole of Copper gives 2 moles of silver.

Moles of Ag = 2 × 0.5 = 1 mole

Mass of Ag = moles × molar mass

= 1 × 107.9

= 107.9g

Therefore, the mass, in grams, of Ag is produced from reaction of 31.75 g of Cu is 107.9g

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Answer:25 grams

Explanation:

The effective nuclear charge (Zeff) for a valence electron in an oxygen atom is calculated using the formula Zeff = Z - S, with Z being the atomic number (8 for oxygen) and S the shielding constant (2 for oxygen). Thus, Zeff for a valence electron in oxygen is 6.

To calculate the effective nuclear charge (Zeff) for a valence electron in an oxygen atom, we first need to know the electron configuration of an oxygen atom. Oxygen has an atomic number of 8, so its electron configuration is 1s2 2s2 2p4. The valence electrons are those in the highest energy level, so for oxygen, they are the four electrons in the 2p orbital.

Using the formula Zeff = Z - S, where Z is the atomic number and S is the shielding constant, we can estimate Zeff for oxygen. Oxygen's atomic number (Z) is 8, and the shielding constant (S) is approximately equal to the number of nonvalence electrons, which for oxygen is 2 (the two electrons in the 1s orbital).

Therefore, Zeff for a valence electron in an oxygen atom is calculated as follows:
Zeff = Z - S = 8 - 2 = 6

The Zeff of 6 means that valence electrons in an oxygen atom experience an effective charge of +6 from the nucleus.

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Answer:

Solar radiation

Explanation:

Umm.. i just guessed and got the question right so...sksksks

look at the picture below for the anwse

Answer:

D

Explanation:

just took the test

The venn diagram illustrates D) Atoms are the most basic form of matter. They combine to form larger electrically stable compounds.

Material / Substance can be divided into 2 parts namely a single substance and a mixture. A single substance can be an element or a compound. While the mixture can be a homogeneous or heterogeneous mixture.

1. Elements are: A group of atoms that have the same number of protons in their nucleus (atomic number). The element is a single substance that can no longer be divided into smaller parts.

2. Compounds: a single substance consisting of several elements. Compounds are formed from at least 2 different elements

3. Mixed: material consisting of two or a single substance (from elements and compounds)

Let see the answer choices :

A) Compounds are found inside the matter of atoms.

Inside the atom consists of a nucleus containing 3 basic particles namely protons and neutrons, while electrons move around the nucleus.

So the statement is false

B) A pure substance may contain subatomic particles but not atoms.

Subatomic particles inside the atoms, so a pure substance contain atoms

So the statement is false

C) Compounds are the most basic form of matter

the most basic form of matter is atom

So the statement is false

D) Atoms are the most basic form of matter. They combine to form larger electrically stable compounds.

Compounds can consist of several atoms

So the statement is true

The subatomic particle that has the least mass

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The part of an atom that is mostly empty space

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To determine if an unknown compound is an alcohol using its IR spectrum, look for a distinct broad O-H stretch in the 3300 to 3400 cm⁻¹ range indicative of hydrogen bonding, and a strong C-O stretch. These features differentiate alcohols from other compounds with similar functional groups.

If you examine the IR spectrum of an unknown and want to determine if it is an alcohol, look for two key features: the O-H stretch and the C-O stretch. Alcohols are characterized by a very broad, strong O-H stretch in the range of 3300 to 3400 cm⁻¹, which is indicative of hydrogen bonding within the alcohol.

Additionally, alcohols exhibit a strong C-O stretch typically around 1000 to 1300 cm⁻¹. Unlike ethers and epoxides, which also display a C-O stretch, alcohols can be distinguished by the presence of the broad O-H stretch.

The exact position and the breadth of the O-H absorption can vary based on the level of hydrogen bonding, thus providing further clues about the structure of the unknown alcohol. To confirm the identity, comparing the IR spectrum of the unknown sample against known standards can be very helpful.

Answer:

15.8528 grams of oxygen will be obtained.

Explanation:

[tex]4C_3H_5N_3O_9\rightarrow 6N_2+12CO_2+10H_2O+O_2[/tex]

Mass of nitroglycerin = [tex]4.50\times 10^{2} g[/tex]

Moles of nitroglycerin:

[tex]\frac{4.50\times 10^{2} g}{227.08 g/mol}=1.9816 mol[/tex]

According to reaction, 4 moles of nitroglycerin gives 1 mole of oxygen gas.

then 1.9816 mol of nitroglycerin will give:

[tex]\frac{1}{4}\times 1.9816=0.4954 [/tex] moles of oxygen gas.

Mass of oxygen ;

[tex]0.4954 mol\times 32 g/mol=15.8528 g[/tex]

15.8528 grams of oxygen will be obtained.

The maximum mass of O₂ that can be obtained from 4.5×10² g of nitroglycerin is 15.86 g

The balanced equation for the reaction is given below:

Next, we shall determine the mass of C₃H₅N₃O₉ that decomposed and the mass of O₂ produced from the balanced equation. This can be obtained as follow:

Molar mass of C₃H₅N₃O₉ = (12×3) + (5×1) + (14×3) + (16×9)

= 36 + 5 + 42 + 144

= 227 g/mol

Molar mass of O₂ = 2 × 16 = 32 g/mol

From the balanced equation above,

908 g of C₃H₅N₃O₉ decomposed to produce 32 g of O₂.

Finally, we shall determine the mass of O₂ that will be produce from the decomposition of 4.5×10² g of C₃H₅N₃O₉. This can be obtained as follow:

From the balanced equation above,

908 g of C₃H₅N₃O₉ decomposed to produce 32 g of O₂.

Therefore, 4.5×10² g of C₃H₅N₃O₉ will decompose to produce = [tex]\frac{4.5*10^{2} * 32}{908}[/tex] = 15.86 g of O₂

Thus, the maximum mass of O₂ obtained from 4.5×10² g of nitroglycerin is 15.86 g

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The length of DC is 10 units and the measure of angle ∠C is 74°.

To find the length of DC, we can use the concept of similar triangles. Since triangles ΔABC and ΔDEF are similar, the corresponding sides are proportional. We can set up the following proportion: AB/DE = BC/EF = AC/DF. Plugging in the given lengths, we have 5/3 = BC/6. Cross-multiplying gives us BC = 10 units. Therefore, the length of DC is 10 units.

To find the measure of angle ∠C, we can use the fact that corresponding angles in similar triangles are congruent. Since angle ∠B = 53° in ΔABC, we know that angle ∠F = 53° in ΔDEF. Therefore, angle ∠C = 180° - 53° - 53° = 74°.

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Answer is: Huge stadium with a positively charged marble at the center.

According to Rutherford model of the atom:

1) Atoms have their charge concentrated in a very small nucleus.

2) Major space in an atom is empty.

3) Atoms nucleus is surrounded by negatively charged particles called electrons.

4) An atom is electrically neutral.

Final answer:

Ethanol and 1-decanol both possess a hydroxyl group and are classified as primary alcohols. They also both have the capability for hydrogen bonding, influencing their physical properties.

Explanation:

Both ethanol and 1-decanol share common structural features. Firstly, they both possess a hydroxyl group (-OH) connected to an aliphatic carbon chain, which categorizes them as alcohols. Ethanol is a two-carbon alcohol with the molecular formula CH3CH2OH, while 1-decanol is a longer ten-carbon chain alcohol with the formula CH3(CH2)9OH. The similarity lies in the fact that for both ethanol and 1-decanol, the hydroxyl group is positioned at the end of the carbon chain (primary alcohols). Additionally, both alcohols have the potential for hydrogen bonding due to the presence of the hydroxyl group, affecting their physical properties such as boiling point and solubility in water.

Answer: 81.8 g/mol

Explanation:

We’re being asked to calculate the molar mass of an unknown acid based on our interpretation of the titration curve.  

Recall that at the equivalence point of a titration:

[tex]moles\ acid=moles\ base[/tex]

We can use this equation to calculate the moles of the unknown acid. Since the unknown acid only has a single Ka value, it is a monoprotic acid, which means there will be one equivalence point for the titration.

Mole-to-mole comparison: A mole-to-mole comparison will then show that 1 mole of the unknown acid reacts with 1 mole of Na(OH).

Molarity of NaOH: The molarity of NaOH (the base) is given as 0.112 M or 0.112 mol/L NaOH.

As for the volume of NaOH (the base) added, we can interpret this from the graph:  

we can see that at the equivalence point, 25 mL of the vase was added.

Vbase is more or less 25.00 mL

Recall:  

1 mL = 10-3 L  

Solving for MMacid:  

Again, at the equivalence point of a titration:

[tex]moles\ acid=moles\ base=0.112*25*10^{-3}[/tex]

[tex]moles\ acid = 0.0028\ moles[/tex]

Molar mass is defined as the mass in grams of one mole of a substance.  

The units of molar mass are grams per mole, abbreviated as g/mol and uses the formula below:

[tex]molar\ mass=\frac{mass\ of\ compound\ in\ grams}{mole\ of\ compound\ in\ moles}[/tex]

[tex]=\frac{mass\ of\ acid}{moles\ acid}[/tex]

[tex]=\frac{0.229g}{0.0028mol}[/tex]

molar mass acid = 81.8 g/mol

The molar mass of the unknown acid is 81.8 g/mol.

An acid that donates a single hydrogen atom or proton is called monoprotic acid. The molar mass of the unknown acid in titration is 81.8 gm/mol.

The molar mass of any substance is the ratio of the mass of the substance in grams and moles of the same substance in mol. The molar mass is given by g/mol.

In titration, the moles of acid are equivalent to acid and can be used to determine the moles of the unknown acid from the base.

We know, that the molarity of base (NaOH) is 0.112 M, and the graph is used to know the volume to be 25 ml.

The moles of the base is calculated as:

[tex]\begin{aligned} \rm moles &=\rm molarity \times volume\\\\&= 0.112 \;\rm M \times 25 \times 10^{-3}\;\rm L\\\\&= 0.0028\;\rm moles\end{aligned}[/tex]

Hence, moles of acid is 0.0028 mol.

The molar mass of acid is calculated as:

[tex]\begin{aligned}\rm Molar \;mass &= \rm \dfrac{mass}{moles}\\\\&= \dfrac{0.229}{0.0028}\\\\&= 81.8\;\rm g/mol\end{aligned}[/tex]

Therefore, 81.8 g/mol is the molar mass of unknown monoprotic acid.

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The statement is likely false. The entropy of a substance generally increases with its molecular complexity and size, suggesting C₂H₅OH(l) would have higher entropy than CH₃OH(l). Additionally, the physical state (solid, liquid, gas) impacts entropy, but in this case, both substances are liquids.

The statement that 1 mole of CH₃OH(l) has a greater entropy than 1 mole of C₂H₅OH(l) is likely false. Entropy, a measurement of disorder or randomness in a system, generally increases with the complexity and size of a molecule. For example, a larger molecule with more atoms (like C₂H₅OH, also known as ethanol) typically has more potential arrangements or microstates, leading to a higher entropy than a smaller, less complex molecule (like CH₃OH, also known as methanol).

Furthermore, it should be noted that the physical state can significantly impact entropy. In general, gases have higher entropy than liquids, which in turn, have higher entropy than solids due to the increased disorder and freedom of movement in these states. However, as both substances in this case are in the liquid state, the primary factor influencing the entropy is likely the size and complexity of the molecule.

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The statement 1 mole of CH3OH(l) has a greater entropy than 1 mole of C2H5OH(l) is False.

To understand why this statement is false, let's consider the factors that affect the entropy of a substance. Entropy is a measure of the disorder or randomness in a system. In general, for liquids, the larger the molecule, the more ways there are for the molecules to arrange themselves, leading to higher entropy.

CH3OH, methanol, has a molar mass of approximately 32.04 g/mol, while C2H5OH, ethanol, has a molar mass of approximately 46.07 g/mol. Since ethanol has a larger molecule than methanol, it is expected to have a higher entropy due to the increased number of possible arrangements of its molecules in the liquid state.

Furthermore, experimental data supports this expectation. The standard molar entropy (S°) for methanol (CH3OH) at 298 K is about 126.8 J/(mol·K), while the standard molar entropy for ethanol (C2H5OH) at 298 K is about 160.7 J/(mol·K). Therefore, ethanol has a higher entropy than methanol in the liquid state.

In conclusion, 1 mole of C2H5OH(l) actually has a greater entropy than 1 mole of CH3OH(l), making the original statement false.

Oxygen is essential for life, but too much can be harmful. Lack of oxygen leads to brain damage and death. The optimal level for supporting life is about 20% oxygen in the atmosphere.

Oxygen is a vital component for life and is necessary for the chemical reactions that keep our bodies alive. It is a key player in the production of ATP, which is the energy currency of cells. Lack of oxygen can lead to brain damage within minutes and death within a short period of time.

While oxygen is essential for life, too much of it can be harmful. Pure oxygen at high concentrations can be toxic and cause damage to cells. The atmosphere contains about 20% oxygen, which is the optimal level for supporting life.

It is incorrect to say that less oxygen on Earth would lead to longer life spans. In fact, organisms require a certain amount of oxygen to survive and thrive. Oxygen is necessary for the process of respiration, which generates energy for the body.

Mark him brainliest, please. Don't be afraid to ask how. I know how to.

For the recrystallization of naphthalene, ethanol is likely more effective than hexane due to its ability to form hydrogen bonds and its polar nature, allowing for better dissolution when heated and potentially higher recovery rates.

The effectiveness of a solvent in the recrystallization of naphthalene depends on the solubility of naphthalene in that solvent at different temperatures. For recrystallization, a solvent in which the desired compound is slightly soluble when cold but more soluble when hot is ideal. Ethanol is a polar solvent that can form hydrogen bonds and therefore, can dissolve a wide range of organic compounds, including naphthalene, more effectively when heated.

Whereas, hexane is nonpolar and might not be as effective at dissolving naphthalene, especially if the substance is more polar. Based on solubility profiles and hydrogen bonding capabilities, ethanol would likely be a more effective solvent for recrystallization of naphthalene compared to hexane.

Answer : The mass of iron(III)sulfide is, 5.4288 g

Solution : Given,

Mass of iron, Fe = 3 g

Mass of sulfur, [tex]S_8[/tex] = 2.5 g

Molar mass of Fe = 56 g/mole

Molar mass of [tex]S_8[/tex] = 256 g/mole

Molar mass of iron(III)sulfide, [tex]Fe_2S_3[/tex] = 208 g/mole

[tex]16Fe(s)+3S_8(s)\rightarrow 8Fe_2S_3(s)[/tex]

First we have to calculate the moles of iron and sulfur.

[tex]\text{ Moles of Fe}=\frac{\text{ Mass of Fe}}{\text{ Molar mass of Fe}}=\frac{3g}{56g/mole}=0.054moles[/tex]

[tex]\text{ Moles of }S_8=\frac{\text{ Mass of }S_8}{\text{ Molar mass of }S_8}=\frac{2.5g}{256g/mole}=0.0098moles[/tex]

16 moles of Fe react with 3 moles of [tex]S_8[/tex]

0.054 moles of Fe react with [tex]\frac{3}{16}\times 0.054=0.010125[/tex] moles of [tex]S_8[/tex]

Therefore, the excess reagent in this reaction is, Fe and limiting reagent is, [tex]S_8[/tex]

Now we have to calculate the moles of FeS.

As, 3 moles of [tex]S_8[/tex] gives 8 moles of [tex]Fe_2S_3[/tex]

So, 0.0098 moles of [tex]S_8[/tex] gives [tex]\frac{8}{3}\times 0.0098=0.0261[/tex] moles of [tex]F_2eS_3[/tex]

The moles of [tex]Fe_2S_3[/tex] = 0.0261 moles

Now we have to calculate the mass of [tex]Fe_2S_3[/tex].

Mass of [tex]Fe_2S_3[/tex] = Moles of [tex]Fe_2S_3[/tex] × Molar mass of [tex]Fe_2S_3[/tex]

Mass of [tex]Fe_2S_3[/tex] = 0.0261 g × 208 g/mole = 5.4288 g

Therefore, the mass of iron(III)sulfide is, 5.4288 g

Answer:

2Cu(s)+S(s)→Cu2S(s)

Explanation:

The chemical equation for the reaction between solid copper  and solid sulfur to form solid copper(i) sulfide is 2Cu(s) + S(s) -> Cu₂S(s)

The chemical equation for the reaction between solid copper and solid sulfur to form solid copper(i) sulfide can be written as follow:

Solid copper + Solid sulfur -> Solid copper(i) sulfide

Cu(s) + S(s) -> Cu₂S(s)

There are 2 atoms of Cu on the right side and 1 atom on the left. It can be balanced by writing 2 before Cu as shown below:

2Cu(s) + S(s) -> Cu₂S(s)

Thus, the balance equation for the reaction is 2Cu(s) + S(s) -> Cu₂S(s)

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