8 original questions from New Regents. The worksheet, answer key, and browser practice are free.
Molar Mass and Mole Conversions 4 questions
Molar Mass and Mole Conversions
New Regents original practice • Name: ____________________ Date: __________ Show your work for written answers.
Use atomic masses from the 2025 periodic table. For a pure substance, n = m/M, where M is its molar mass in grams per mole.
Question 1
What is the molar mass of MgCl₂?
- 59.76 g/mol
- 70.90 g/mol
- 83.32 g/mol
- 95.21 g/mol
Question 2
Calculate the mass of 0.240 mol of H₂O. Show the molar mass and conversion.
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Question 3
How many oxygen atoms are counted per formula unit of Ca(NO₃)₂ when finding its molar mass? Explain how the subscripts apply.
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Question 4
How many moles of CO₂ are in a 22.0 g sample? Round to three significant figures.
- 0.250 mol
- 0.500 mol
- 2.00 mol
- 44.0 mol
Comparing Solid Samples 4 questions
Comparing Solid Samples
Use the information below to answer the questions.
A stockroom labels three pure solid samples. Use the masses in the table to compare the amount of each compound.
| Sample | Compound | Mass (g) |
|---|---|---|
| P | NaCl | 29.22 |
| Q | KCl | 37.28 |
| R | NaCl | 58.44 |
Question 5
Calculate the amount, in moles, of NaCl in sample P. Show the molar mass and conversion.
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Question 6
Which pair contains approximately the same number of moles of compound?
- P and Q
- P and R
- Q and R
- All three samples
Question 7
Explain why sample Q can have a greater mass than sample P yet contain about the same number of moles.
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Question 8
If half of sample R is removed, how many moles of NaCl remain?
- 0.2500 mol
- 0.5000 mol
- 1.000 mol
- 2.000 mol
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