Formula Mass
Molecules
Mass
What is the formula?
Percent Composition
100

What is the formula mass of silver sulfate

312 grams

100

How many carbon dioxide molecules are in 4.42 moles of the gas?

2.66x1024

100

How many moles are there in 125g of sulfuric acid (H2SO4)?

1.28 moles

100

What is the empirical formula of a compound that contains 7.83g of carbon, 2.0g of hydrogen, and 5.21g of oxygen?

C2H6O

100

What is the percent by mass of nitrogen in N2O?

64%

200

What is the formula mass of NH4C2H3O2?

77 grams

200

How many molecules are in 1.5 moles of water?

9.03 x 1023 molecules

200

How many grams are there in 1.5 x 1023 molecules of CO2?

11 grams

200

The empirical formula is CH.  Its molar mass is 26.  What is its molecular formula?

C2H2

200

What is the percent by mass of oxygen in CH3OH?

50.0 %

300

What is the molecular mass of (NH4)2SO4

132 grams

300

What is the number of atoms in 46 grams of sodium?

1.204 x 1024 atoms

300

How many moles are in 25 g of NaCl?

0.427 moles

300

The empirical formula of a substance is CH2O.  The molar mass is 180.  What is the molecular formula?

C6H12O6

300

What percent mass is nitrogen in Mg(CN)2?

36.8%

400

Calculate the gram formula mass of CaSO4 + 2H2O

172 grams

400

9.25x 1022 water molecules are produced from a reaction.  How many moles is this?

0.154 mole

400

A box of baking soda (NaHCO3) contains 250 grams.  How many moles of baking soda are in the box?

3 moles

400

What is the empirical formula of a molecule contains 65.5% carbon, 5.5% hydrogen, and 29.0% oxygen?

C3H3O

400

What is the percent by mass of water in the hydrate Na2CO10H2O?

62.9%

500

Calculate the gram formula mass of ammonium carbonate

(NH4)2CO3

96

500

The number of molecules contained in 0.2 mole of N2 at STP is

1.204 x 1023 molecules

500

A container of sodium phosphate contains 500g of powder.  How many moles are in the container?

Na3PO4

3.05 moles

500

A 60g sample of tetraethyl lead is found to contain 38.43g lead, 17.83g carbon, and 3.74 g hydrogen.  Find its empirical formula.

PbC8H21

500

A 9.3g sample of a hydrated salt is heated until it has a constant mass of 7.14g.  What is the percent by mass of the water contained in the original sample?

23.2%

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