Q: Which equation correctly relates the number of molecules to moles?

$$\text{Number of molecules} = \text{moles} \times 6.022 \times 10$$^{23}$$

Q: Which of the following is a correct use of a chemical formula as a conversion factor?

$$\dfrac{3\ \text{leaves}}{1\ \text{clover}}$$

Question 1

What is the molar mass of water ($$\mathrm{H_2O}$$)?

Accepted Answer

$$18.02\ \mathrm{g/mol}$$

Question 2

How many grams are present in $$1.75$$ moles of water ($$\mathrm{H_2O}$$)?

Accepted Answer

$$31.5\ \mathrm{g}$$

Question 3

Which equation correctly relates the number of molecules to moles?

Accepted Answer

$$	ext{Number of molecules} = 	ext{moles} 	imes 6.022 	imes 10$$^{23}$$

Question 4

Calculate the mass in grams of $$4.78 	imes 10$$^{24}$$ molecules of $$\mathrm{$$NO_2$$}$$.

Accepted Answer

$$365\ \mathrm{g}$$

Question 5

What is the correct conversion factor to use when converting from moles of $$\mathrm{H_2O} to $$grams of $$\mathrm{H_2O}$$?

Accepted Answer

$$\dfrac{18.02\ \mathrm{g\ H_2O}}{1\ \mathrm{mol\ H_2O}}$$

Question 6

If you have $$1.7$$ moles of $$\mathrm{$$CaCO_3$$}$$, how many moles of oxygen atoms are present?

Accepted Answer

$$5.1\ \mathrm{mol}$$

Question 7

A sample contains $$15\ \mathrm{g} of$$ $$\mathrm{NaCl}. $$How many grams of sodium are present in the sample?

Accepted Answer

$$5.9\ \mathrm{g}$$

Question 8

Which of the following best describes the molar mass of a compound?

Accepted Answer

The sum of the atomic masses of all atoms in one mole of the compound

Question 9

How many leaves are there on $$14$$ clovers if each clover has $$3$$ leaves?

Accepted Answer

$$42$$

Question 10

Which of the following is Avogadro’s number?

Accepted Answer

$$6.022 	imes 10$$^{23}$$

Question 11

A chemist has $$58.44\ \mathrm{g} of$$ $$\mathrm{NaCl}. $$How many moles of $$\mathrm{NaCl}$$ does this represent?

Accepted Answer

$$1.00\ \mathrm{mol}$$

Question 12

Which step is necessary to convert grams of a compound to number of molecules?

Accepted Answer

Convert grams to moles, then moles to molecules using Avogadro’s number

Question 13

What is the formula mass of $$\mathrm{NO_2$}$$?

Accepted Answer

$$46.01\ \mathrm{g/mol}$$

Question 14

If you have $$2.5$$ moles of $$\mathrm{CO_2$}$$, how many moles of oxygen atoms do you have?

Accepted Answer

$$5.0\ \mathrm{mol}$$

Question 15

A patient receives $$36.04\ \mathrm{g} of $$glucose ($$\mathrm{C_6H_{12}O_6$}) in an IV. $$How many moles of glucose did they receive? (Molar mass of glucose = $$180.16\ \mathrm{g/mol})$$

Accepted Answer

$$0.200\ \mathrm{mol}$$

Question 16

Which of the following is a correct use of a chemical formula as a conversion factor?

Accepted Answer

$$\dfrac{3\ 	ext{leaves}}{1\ 	ext{clover}}$$

Question 17

How many molecules are present in $$2.00$$ moles of $$\mathrm{CO_2$}$$?

Accepted Answer

$$1.204 	imes 10$$^{24}$$

Question 18

Which of the following best explains why the molar mass of $$\mathrm{H_2O} is$$ $$18.02\ \mathrm{g/mol}$$?

Accepted Answer

It is the sum of the masses of two hydrogen atoms and one oxygen atom in one mole of water

Question 19

A student has $$4.00$$ moles of $$\mathrm{NaCl}. $$How many moles of sodium atoms are present?

Accepted Answer

$$4.00\ \mathrm{mol}$$

Chemical Composition: Conversions Between Mass, Moles, and Molecules

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