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Representative Particles
Volume
Molar Mass
Using Mole Ratios
Empirical and Molecular Formulas
100

How many moles are in 1.75 x 1023 atoms of Cl?

0.291 moles Cl

100

What is the volume in liters of 3.15 mol carbon dioxide, CO2, at STP?

70.6 L CO2

100

How many moles are in 24.15g of Mg?

0.993 mol Mg

100

If you have 4.5 moles of sodium, how many moles of chlorine do you need to completely react with the sodium? 

Na + Cl --> NaCl

4.5 moles Cl

100

Calculate the percent composition of Ca3P2. 

%Ca=65.9%  and %P=34.1%

200

Determine the number of moles in 4.35 x 1024 formula units of PbSO4.

7.22 mol PbSO4

200

At STP, one mole of gas occupies what volume?

22.4 L at STP

200

What is the mass in grams of 2.50 mol S?

80.2g S

200

If you have 3 moles of O2 how many moles of MgO can be formed?

2Mg + O2 --> 2MgO

6 mol MgO

200

Determine the percent composition of Ca3(PO4)2.

%Ca= 38.7% , %P= 20%, and %O= 41.3%

300

How many formula units are in 6.70g Na2SO4?

2.84 x 1022 formula units Na2SO4

300

How many liters of oxygen gas, O2, are in 8.25g O2 at STP?

5.78L O2 at STP

300

What is the molar mass for Mg(OH)2?

58.3g 

300

If there are 6.2x1023 atoms of calcium carbide (CaC2), what mass of acetylene (C2H2) can be formed?

CaC2   +    2H2O -->    Ca(OH)2 +    C2H2

26.8 g C2H2

300
A compound consists of 29.1% Na, 40.5% S, and 30.4% O. Determine the empirical formula.

Na2S2O3

400

What is the mass in grams of 4.15 x 1023 atoms Ca?

27.6g Ca

400

How many liters would be occupied by 26.3 g NO2 at STP?

12.8 L NO2 at STP

400

What is the mass of 0.500mol aspirin (C9H8O4)?

90.1 g C9H8O4

400

4K + O2 → 2 K2O 

How many moles of diatomic oxygen will be required to consume all 10.12 g of potassium?

0.065 moles O2

400

A compound is composed of 7.2g C, 1.2g H, and 9.6g O. Find the empirical formula.

CH2O

500

How many hydrogen atoms are in 2.65 moles of ethyl alcohol, C2H6O?

9.57 x 1024 atoms H

500

At STP, how many molecules of N2 would be in 16.8L N2?

4.52 x 1023 molecules N2 at STP

500

Calculate the number of moles in 9.315g (NH4)2SO4.

0.07 mol (NH4)2SO4

500

How many grams of lead (II) nitrate are needed to produce 85.25 grams of sodium nitrate?

Pb(NO3)2  +  2NaCl  -->    PbCl2   +    2NaNO3

166 g Pb(NO3)2

500

Combustion analysis gives the following: 26.7% C, 2.2% H, and 71.1% O. If the molar mass of the compound is 180 g/mol, determine the compound's molecular formula. 

C4H4O8