how many reference points are needed to make a thermometer scale?

The number of moles of calcium ions present in a 50.00 mL water sample with hardness of 75.0 ppmis [tex]\boxed{0.00003747{\text{ mol}}}[/tex].

Further Explanation:

The hardness of water is calculated with the use of following formula:

[tex]{\text{Hardness}} = \dfrac{{{\text{Mass}}}}{{{\text{Volume}}}}[/tex]                                                                      …… (1)

Since hardness in given problem occurs due to presence of [tex]{\text{CaC}}{{\text{O}}_{\text{3}}}[/tex], the above formula involves mass of [tex]{\text{CaC}}{{\text{O}}_{\text{3}}}[/tex] and volume of [tex]{\text{CaC}}{{\text{O}}_{\text{3}}}[/tex].

Rearrange equation (1) to calculate mass.

[tex]{\text{Mass}} = \left( {{\text{Hardness}}} \right)\left( {{\text{Volume}}} \right)[/tex]                                                       …… (2)

In case of water, 1 ppm is approximately equivalent to 1 mg/L. Therefore hardness becomes 75.0 mg/L.

Volume is given in mL. It is to be converted into L. The conversion factor for this is,

[tex]1{\text{ mL}} = {10^{ - 3}}{\text{ L}}[/tex]  

Therefore volume of water sample can be calculated as follows:

[tex]\begin{aligned}{\text{Volume of water sample}} &= \left( {50.00{\text{ mL}}} \right)\left( {\frac{{{{10}^{ - 3}}{\text{ L}}}}{{1{\text{ mL}}}}} \right) \\&= 0.05{\text{ L}} \\\end{aligned}[/tex]  

Substitute 75.0 mg/L for hardness and 0.05 L for volume in equation (2) to calculate mass of [tex]{\text{CaC}}{{\text{O}}_3}[/tex].

[tex]\begin{aligned}{\text{Mass of CaC}}{{\text{O}}_{\text{3}}} &= \left( {75.0{\text{ mg/L}}} \right)\left( {0.05{\text{ L}}} \right) \\&= 3.75{\text{ mg}} \\\end{aligned}[/tex]  

Mass of [tex]{\text{CaC}}{{\text{O}}_3}[/tex] is to be converted from mg to g. The conversion factor for this is,

[tex]1{\text{ mg}} = {10^{ - 3}}{\text{ g}}[/tex]  

Therefore mass of [tex]{\text{CaC}}{{\text{O}}_3}[/tex] can be calculated as follows:

 [tex]\begin{aligned}{\text{Mass of CaC}}{{\text{O}}_{\text{3}}} &= \left( {3.75{\text{ mg}}} \right)\left( {\frac{{{{10}^{ - 3}}{\text{ g}}}}{{1{\text{ mg}}}}} \right) \\&= 0.00375{\text{ g}} \\\end{aligned}[/tex]

The formula to calculate moles of [tex]{\text{CaC}}{{\text{O}}_3}[/tex] is as follows:

[tex]{\text{Moles of CaC}}{{\text{O}}_{\text{3}}} = \dfrac{{{\text{Mass of CaC}}{{\text{O}}_{\text{3}}}}}{{{\text{Molar mass of CaC}}{{\text{O}}_{\text{3}}}}}[/tex]                                                    …… (3)

Substitute 0.00375 g for mass of [tex]{\text{CaC}}{{\text{O}}_{\text{3}}}[/tex] and 100.08 g/mol for molar mass of    [tex]{\text{CaC}}{{\text{O}}_{\text{3}}}[/tex] in equation (3).

[tex]\begin{aligned}{\text{Moles of CaC}}{{\text{O}}_{\text{3}}} &= \frac{{{\text{0}}{\text{.00375 g}}}}{{{\text{100}}{\text{.08 g/mol}}}} \\&= 0.00003747{\text{ mol}} \\\end{aligned}[/tex]  

Therefore number of calcium ions present in the given water sample is 0.00003747 mol.

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Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Mole concept

Keywords: CaCO3, mass, volume, hardness, molar mass, moles, mass of CaCO3, 3.75 mg, 0.00375 g, 75.0 ppm, 50.00 mL, 0.00003747 mol

There are 1.05 moles of O²⁻ in 0.350 moles of Al₂O₃.

              1) There is one Ca²⁺ and and two Cl⁻ in one   formula

                  unit of calcium chloride.

             2)There is one mole of Ca²⁺ and and two moles of Cl⁻ in

                one mole of calcium chloride.

The compound in the problem is Al₂O₃. Similar to the example, this chemical formula can be interpreted in two ways:

To determine how many moles of O²⁻ are in 0.350 moles of Al₂O₃, the equation below may be used:

[tex]moles \ of \ O^{2-} = 0.350 \ mol \ Al_2O_3 \times \frac{3 \ mol \ O^{2-}}{1 \ mol \ Al_2O_3}\\\\\boxed {\boxed {moles \ of \ O^{2-} = 1.05 \ mol \ O^{2-}}}[/tex]

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Keywords: moles, mole ratio

Answer:

It shows that the atoms are vibrating in place.

Explanation:

In the crystal, the molecules exhibit a definite position, and they are combined with each other with the help of electrostatic forces. The molecules exhibit certain kind of energy due to which they vibrate in their locations. However, their energy is not that much high to result in overcoming the strong bonding, unless the atoms in the crystals are irradiated or are heated.

Answer:

Sara is taller than Michael.

Explanation:

Height of Sara = 160 cm

Height of Michael = 60 inches

1 inch = 2.54 cm

Height of Micheal = [tex]60 inches=60\times 2.54 cm=152.4 cm[/tex]

160 cm> 152.4 cm

Sara is taller than Michael.

Sara is taller than Micheal

From the question, there are 2.54 centimeters in an inch.

Given this statement, we can convert Sara's height to inches as follows;

2.54 centimeters makes 1 inch

160 centimeters  = 160 centimeters *  1 inch/2.54 centimeters

= 63 inches

Since Micheal is 60 inches tall, Sara is taller than Micheal.

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Answer: The number of molecules present in the given moles of water are [tex]1.054\times 10^{24}[/tex]

Explanation:

We are given:

Moles of water = 1.75 moles

According to mole concept:

1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules.

So, 1.75 moles of water will contain = [tex]1.75\times 6.022\times 10^{23}=1.054\times 10^{24}[/tex] number of molecules.

Hence, the number of molecules present in the given moles of water are [tex]1.054\times 10^{24}[/tex]

Final answer:

The volume of liquid in the graduated cylinder is estimated by reading where the bottom of the meniscus falls on the scale, with typical measurements to the nearest 0.1 mL. In the example provided, estimating the volume as 21.6 mL is reasonable based on the description of the meniscus position.

Explanation:

To measure the volume of a liquid in a graduated cylinder, one must carefully read the measurement at the bottom of the meniscus, which is the curve formed by the liquid surface. For accurate measurement, the cylinder should be at eye level, and the scale should be mentally divided based on the smallest marked division, which typically allows considering smaller subdivisions, usually to one-tenth of a milliliter (0.1 mL).

In this scenario, if the meniscus lies between the 21 and 22 mL marks, closer to the 22-mL mark, an estimate of 21.6 mL would be reasonable. The digits 21 are certain, being the last clear markings, and the '.6' is an estimate that is influenced by how the meniscus appears relative to the 21 and 22 mL markings.

Measuring in Graduated Cylinders

It is essential to understand that different people might provide a slightly different estimation, as some might perceive the meniscus to be equally distant between two markings (estimating the tenth place as 5), while others might see it closer to the following mark (estimating as 7). Since the tenth-place digit is already an estimate, going any finer such as hundredths place would be pointless.

In the table, the highlighted reactants NH3 and Ag2CO3 are Brønsted-Lowry bases, whereas the reactant in the electrolysis of a solution of strontium chloride reaction cannot be determined without more information.

In the table, we have the following reactions:

a) NH3 + HC104
b) Ag2CO3 + HNO3
c) electrolysis of a solution of strontium chloride

From the information given, we can determine the type of reactant for each reaction.

a) NH3 is a weak base and HC104 is a strong acid, so NH3 is a Brønsted-Lowry base.
b) Ag2CO3 is a weak base and HNO3 is a strong acid, so Ag2CO3 is a Brønsted-Lowry base.
c) In this reaction, the type of reactant is not specified, so we cannot determine if it is a Brønsted-Lowry acid or base.

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Answer : There is large empty space between the molecule in a gaseous state as compared to the solid and liquid state.

Explanation :

Solid state : In this state, the molecules are arranged in regular and repeating pattern. The molecules are closely packed that means they are fixed and vibrate in place but they can not move from one place to another.  In the solid, there is no empty space present between the molecules.

Liquid state : In this state, the molecules are present in random and irregular pattern. The molecules are closely packed but they can move from one place to another.  In the liquid, there is a some empty space present between the molecules.

Gaseous state : In this state, the molecules are present in irregular pattern. The molecules are not closely packed and they can move freely from one place to another and spread out. In the gaseous, there is large empty space present between the molecules.

The balanced molecular equation for the neutralization reaction between sulfuric acid (H2SO4) and potassium hydroxide (KOH) is H2SO4(aq) + 2KOH(aq) → K2SO4(aq) + 2H2O(l). This showcases a typical neutralization reaction, where an acid reacts with a base to produce salt and water.

The neutralization reaction between sulfuric acid (H2SO4) and potassium hydroxide (KOH) results in the formation of water (H2O) and potassium sulfate (K2SO4). The reaction's balanced molecular equation is:

H2SO4(aq) + 2KOH(aq) → K2SO4(aq) + 2H2O(l)

This equation is a clear representation of a neutralization reaction where an acid reacts with a base to produce salt and water. In this specific instance, the acid is H2SO4, the base is KOH, the salt is K2SO4, and, of course, the water is H2O.

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The balanced molecular equation for the neutralization reaction between sulfuric acid (H2SO4) and potassium hydroxide (KOH) is H2SO4 (aq) + 2KOH(aq) → K2SO4 (aq) + 2H2O(l). This reaction is a classic example of a neutralization reaction, where an acid reacts with a base to form salt and water.

The neutralization reaction between H2SO4 (sulfuric acid) and KOH (potassium hydroxide) in aqueous solution can be represented as follows:

H2SO4 (aq) + 2KOH(aq) → K2SO4 (aq) + 2H2O(l)

This resulting equation is balanced, meaning the number of atoms of each element is the same on both sides of the equation. In this case, a base (KOH) and an acid (H2SO4) react to form a salt (K2SO4) and water, which is characteristic of a neutralization reaction.

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The mass of helium in the blimps is [tex]\boxed{10.2743{\text{ g}}}[/tex].

Further Explanation:

Density is defined as the mass of the substance per unit volume of the substance. It is represented by the symbol [tex]\rho[/tex]. The density of a substance is calculated as follows:

[tex]\rho = \dfrac{{\text{M}}}{{\text{V}}}[/tex]  

Here,

[tex]\rho[/tex] is the density of the substance.

M is the mass of the substance.

V is the volume of the substance.

The formula to calculate the density of helium is as follows:

[tex]{\text{Density of helium}} = \dfrac{{{\text{Mass of helium}}}}{{{\text{Volume of helium}}}}[/tex]                            …… (1)                                  

Rearrange equation (2) to calculate the mass of helium.

[tex]{\text{Mass of helium}} = \left( {{\text{Density of helium}}} \right)\left( {{\text{Volume of helium}}} \right)[/tex]                …… (2)              

The volume of the blimp is [tex]2.027 \times {10^5}{\text{ f}}{{\text{t}}^3}[/tex]. This is to be converted into L. The conversion factor for this is,

[tex]1{\text{ f}}{{\text{t}}^3} = 28.3168{\text{ L}}[/tex]  

Since the blimp is filled with helium, the volume of the blimp becomes equal to that of helium. Therefore the volume of helium can be calculated as follows:

[tex]\begin{aligned}{\text{Volume of helium}} &= \left( {2.027 \times {{10}^5}{\text{ f}}{{\text{t}}^3}} \right)\left( {\frac{{28.3168{\text{ L}}}}{{1{\text{ f}}{{\text{t}}^3}}}} \right)\\&= 57.3982{\text{ L}}\\\end{aligned}[/tex]  

Substitute 0.179 g/L for the density of helium and 57.3982 L for the volume of helium in equation (2).

[tex]\begin{aligned}{\text{Mass of helium}}&= \left( {{\text{0}}{\text{.179 g/L}}} \right)\left( {{\text{57}}{\text{.3982 L}}} \right)\\&= 10.2743{\text{ g}}\\\end{aligned}[/tex]  

Therefore the mass of helium is 10.2743 g.

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Answer details:

Grade: Middle School

Chapter: Density

Subject: Chemistry

Keywords: density, mass, volume, helium, mass of helium, conversion factor, 10.2743 g, 0.179 g/L.

boiling point is the temp at which a liquid's vapor pressure equals the external pressure. At higher altitudes the external pressure is lower so vapor pressure becomes equal to external pressure at a lower temperature which is why  boiling point decreases with increasing altitude.

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Answer:

8.90

Explanation:

just did it

8.90g/ml is the density of the unknown metal. Mass per unit volume is the definition of a material's density.

Mass per unit volume is the definition of a material's density. Density, or volume per unit volume, is defined as the ratio of mass to volume. It is a way to quantify the amount of "stuff" a given thing contains in relation to its volume (either in cubic metres or cubic centimetres).

In essence, density is an indicator of how closely together matter is packed. The Greek scientist Archimedes is credited with discovering the principle of density, which is simple to calculate if one understands the formula and are familiar with the relevant units.

Density= mass/ volume

Mass of unknown metal = 222.50 g

Volume of unknown metal = 25.00ml

Density= 222.50/ 25.00

        = 8.90g/ml

Therefore, 8.90g/ml is the density of the unknown metal.

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Final answer:

The probability of four 13C isotopes being adjacent to each other in a benzene molecule, given their natural molar abundance of roughly 1%, is extremely low at 1x10⁻⁸, due to the need for this specific arrangement to occur consecutively.

Explanation:

The question asks about the probability of four 13C isotopes being adjacent to each other in a benzene molecule. Given that the natural molar abundance of 13C is roughly 1%, the probability of any given carbon atom in benzene being 13C is 0.01. Since benzene has a ring structure with 6 carbon atoms, the probability of any specific sequence of four carbon atoms being all 13C can be calculated using the multiplication rule of probability.

To find the probability of four 13C isotopes in a row, we raise the single-event probability (0.01) to the fourth power because we need this event to happen four times consecutively for four specific carbon atoms:

Probability = 0.01⁴ = 0.00000001 or 1x10⁻⁸

This calculation shows that the probability is extremely low, reflecting the rare occurrence of such an event due to the low natural abundance of 13C.

The maximum amount of O2 that can be obtained from 227 g of nitroglycerin is 907 grams. The percent yield of O2 in this reaction is 0.72%.

Nitroglycerin decomposes according to the following reaction:

2 C3H5N3O9 → 3 N2 + 5 H2O + 7 CO + 7 C

To determine the maximum amount of O2 that can be obtained from a given amount of nitroglycerin, we need to calculate the molar mass of nitroglycerin and find the stoichiometric ratio between O2 and nitroglycerin. The molar mass of nitroglycerin is approximately 227 g/mol. From the balanced equation, we can see that 2 moles of nitroglycerin produce 7 moles of O2. Therefore, if we have 227 grams of nitroglycerin, we can calculate the amount of O2 produced as follows:

(227 g nitroglycerin) * (7 moles O2 / 2 moles nitroglycerin) * (32 g O2 / 1 mole O2) = 907 g O2

So, the maximum amount of O2 that can be obtained from 227 g of nitroglycerin is 907 grams.

To calculate the percent yield, we compare the actual yield (6.55 g) to the theoretical yield (907 g) and calculate the percentage:

Percent Yield = (Actual Yield / Theoretical Yield) * 100%

Percent Yield = (6.55 g / 907 g) * 100% = 0.72%

0.73g of H2 reacts with 3.28g of O2 to produce approximately 3.69g of H2O according to the stoichiometry of the chemical reaction 2H2 + O2 → 2H2O.

The subject of this question is a chemical reaction involving molecular hydrogen (H2) and molecular oxygen (O2) to produce water (H2O). The equation for this reaction is 2H2 + O2 → 2H2O. It implies that 2 moles of hydrogen react with 1 mole of oxygen to form 2 moles of water.

Using molar mass, we can find that 0.73g of H2 is approximately 0.36 moles, and 3.28g of O2 is about 0.205 moles. However, according to the stoichiometry of the reaction, one mole of oxygen should react completely with 2 moles of hydrogen to form 2 moles of water. Thus, in this case, hydrogen is in excess and oxygen is the limiting reactant. Therefore, we can find the mass of water produced by multiplying the number of moles of oxygen (the limiting reactant) by the molar mass of water (18.01528g/mol), which is approximately 3.69 grams.

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Answer : Inorganic Chemist.

Explanation : When Joseph Priestly discovered and described the chemical properties of oxygen, then he would be considered as inorganic chemist.

As the physical and chemical properties of elements are studied under the branch of inorganic chemistry, therefore he would be considered as an inorganic chemist.