Practice Grams (Mass) in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

A gram (g) is the standard working unit of mass in chemistry, defined as one thousandth of a kilogram (the SI base unit of mass).

Grams tell you how heavy something is. A paperclip is about 1 gram. Moles tell you how many particles you have—a completely different question.

Showing a random 20 of 50 problems.

Example 1

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In 2H2+O2→2H2O2H_2 + O_2 \rightarrow 2H_2O, how many grams of water form from 4 g4\text{ g} H2H_2? (H2=2H_2=2, H2O=18 g/molH_2O=18\text{ g/mol})

Example 2

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A mixture contains 4 g4\text{ g} He (M=4M=4) and 28 g28\text{ g} N2N_2 (M=28M=28). What is the total number of moles, and the mass percent of He?

Example 3

easy
How many grams are in 2 mol2\text{ mol} of carbon (M=12 g/molM=12\text{ g/mol})?

Example 4

easy
Convert 250 mg250\,\text{mg} to grams.

Example 5

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How many grams of glucose (C6H12O6\text{C}_6\text{H}_{12}\text{O}_6, M=180 g/molM=180\,\text{g/mol}) are needed to prepare 0.500 L0.500\,\text{L} of a 0.250 M0.250\,\text{M} solution?

Example 6

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What is the mass percent of N in NH4_4NO3_3 (M=80M=80, atomic N=14)?

Example 7

easy
Convert 0.75 g0.75\text{ g} to milligrams.

Example 8

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In N2+3H2→2NH3\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3, how many grams of NH3_3 (M=17M=17) form from 14 g14\,\text{g} of N2_2 (M=28M=28)?

Example 9

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How many grams of O2O_2 react with 0.25 mol0.25\text{ mol} CH4CH_4 in CH4+2O2→CO2+2H2OCH_4 + 2O_2 \rightarrow CO_2 + 2H_2O? (O2=32O_2=32)

Example 10

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How many grams are in 0.30 mol0.30\text{ mol} of H2SO4H_2SO_4 (M=98 g/molM=98\text{ g/mol})?

Example 11

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How many grams of CaCO3_3 (M=100M=100) form from 0.40 mol0.40\,\text{mol} Ca in Ca+C+32O2→CaCO3\text{Ca} + \text{C} + \frac{3}{2}\text{O}_2 \rightarrow \text{CaCO}_3?

Example 12

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How many grams of H2_2O (M=18M=18) form from burning 32 g32\,\text{g} CH4_4 (M=16M=16) in CH4+2O2→CO2+2H2O\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}?

Example 13

easy
Convert 2.502.50 moles of sodium chloride (NaCl) to grams. (Molar mass of NaCl = 58.44 g/mol58.44\,\text{g/mol})

Example 14

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Find the molar mass of Ca(NO3)2\text{Ca}(\text{NO}_3)_2 (Ca=40, N=14, O=16\text{Ca}=40,\,\text{N}=14,\,\text{O}=16).

Example 15

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How many moles are in 25.0 g25.0\,\text{g} of NaCl (M=58.5M=58.5)?

Example 16

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What mass of CC (M=12M=12) contains the same number of moles as 32 g32\text{ g} of O2O_2 (M=32M=32)?

Example 17

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How many milligrams are in 0.075 g0.075\,\text{g}?

Example 18

easy
What is the molar mass of MgO (Mg=24, O=16\text{Mg}=24,\,\text{O}=16)?

Example 19

easy
How many grams are in 3 mol3\text{ mol} of oxygen gas O2O_2 (M=32 g/molM=32\text{ g/mol})?

Example 20

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How many moles are in 49.049.0 g of sulfuric acid (H2SO4\text{H}_2\text{SO}_4)? How many molecules does this represent? (Molar mass = 98.09 g/mol98.09\,\text{g/mol})
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Related Concepts

MoleMolar Mass