A-Level Calculating Mass of a Substance

What is the definition of molar mass?

• number of grams per one mole of a substance
• whole number ratio that is a multiple of a chemical formula
• simplest, whole number ratio of a chemical formula
• 6.02 x 10^23 particles per one mole of a substance

Tags

NGSS.HS-PS1-7

How many atoms are present in a 13.5 gram sample of beryllium?

• 1.5 particles

• 9 particles

• 4.03 x10²³ particles

• 9.02 x10²³ particles

A sample of silver contains 5.71 x 10²² atoms. How many moles of silver are present?

• 3.43 x 10⁴⁶ moles

• 0.0529 moles

• 0.0948 moles

• 10.5 moles

A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?

• Mg₄N₃
• MgN₂
• Mg₃N₂ 
• MgN

2.40 g of an explosive, J, contains 0.473 g of nitrogen. J also contains 33.8% carbon and 1.41% hydrogen by mass. The remainder of J is oxygen.

What is the empirical formula of J?

• C₄HNO₂

• CH₂N₂O

• C₂HNO₂

• CHNO

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

Cl₂ + 2 KBr → Br₂ + 2 KCl
How many grams of potassium chloride can be produced from 356 g of chlorine and 356 g of potassium bromide?

• 749 g
• 223 g
• 479 g
• 814 g

Tags

NGSS.HS-PS1-7

If a chemist calculates the maximum amount of product that could be obtained in a chemical reaction, he or she is calculating the

• theoretical yield
• mole ratio
• actual yield
• percentage yield

Tags

NGSS.HS-PS1-7

2 KClO₃ → 2 KCl + 3 O₂
How many moles of oxygen are produced when 6.7 moles of KClO₃ decompose completely?

• 6.7 mol
• 1.0 mol
• 10.1 mol
• 4.5 mol

Tags

NGSS.HS-PS1-7

At RTP, 1 mol, or representative particles, of any gas occupies a volume of......................

• 24 dm3

• 44 dm3

• 22 dm3

What volume of hydrogen will be produced at RTP by the reaction 67.3 g of magnesium with excess water according to the following reaction?

Mg + 2H₂O --> Mg(OH)₂ + H₂

Ar values: Mg=24.3, H=1, O=16

R= 8.31

• 68.5 dm3

• 66.5 dm3

• 33.2 dm3

• 137 dm3