Chemistry Unit 7 Review - Desena

Mass Conversions

100

When doing mass conversions, what do you need to know about the compound/element?

Molar Mass

200

What is the molar mass of HCl?

36.46 g/mol

300

What is the mass of 2.56 moles of sodium hydroxide?

102 g

400

How many moles are in 75.4 g of H₂SO₄?

0.769 moles

500

How many moles are in 92.1 g of hydrogen phosphate?

1.12 moles

Avogadro's Number

100

What is Avogadro's Number?

6.022 * 10²³

200

How many moles are in 7.07*10²³ atoms of nitrogen?

1.17 moles

300

How many atoms are in 1.5 moles of silver?

9.0*10²³ atoms

400

How many moles are in 3.0*10²⁵ representative particles of sugar?

50 moles

500

How many representative particles of salt are in 9.89 moles?

5.96*10²⁴ representative particles

Volume Conversion

100

What is the constant to convert moles to liters?

22.4 L

200

What are the units used for volume 

L for Liters 

300

What is STP and why is it important?

standard temp and pressure. 0 degrees celsius and 1 atm. This lets us know that we do not need to account for pressure and temp in our equation 

400

At STP, what is the volume of 0.58 moles of HCl gas?

13 L

500

At STP, how many moles are in 110.2 L of bromine gas?

4.92 moles

Percent Composition

100

What is percent composition useful for?

Determining the chemical formula

200

A 13.60 g sample of a compound, containing only magnesium and oxygen, is decomposed. There was 5.40 g of oxygen obtained during the decomposition. What is the percent composition of this compound?

39.7% O

60.3% Mg

300

What is the percent composition of Na₂S₂O₃? 

% Na = 29.1%

% S = 40.6%

% O = 30.4%

400

What is the mass of chlorine and hydrogen in 56 g of HCl? The percent composition is 2.8% H and 97.2% Cl

1.6 g H

54.4 g Cl

500

A 3.56 g sample of pure iron powder was heated in gaseous chlorine, and 10.39 g of an iron chloride was formed. What is the percent composition of this compound?

34.3% Fe

65.7% Cl

Empirical vs Molecular Formula

100

H₂O₂ is an example of which type of formula?

Molecular

200

What is the empirical for C₆H₁₂O₆?

CH₂O

300

Determine the empirical formula for a compound with the following percent composition:

15.8% carbon and 84.2% sulfur

CS₂

400

Determine the empirical formula for a compound with the following percent composition:

67.9% C, 5.70% H, 26.4% N  

C₃H₃N

500

A major textile dye manufacturer developed a new yellow dye. The dye has a percent composition of 75.95% C, 17.72% N, and 6.33% H by mass with a molar mass of about 240 g/mol. Determine the molecular formula of the dye.  

C₁₅H₁₅N₃