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mixed mole and percent comp homework

Total questions: 28

Worksheet time: 1hrs 5mins

Name
Class
Date
1.

How many molecules are in 2.5 mol of NaCl?

a)

1.50 x1024 molecules

b)

1.50 molecules

c)

4.15 molecules

d)

1.51 x1024 molecules

2.

How many moles are in 19.82 g Mg?

a)

1.23 mol Mg

b)

481.70 mol Mg

c)

1.00 mol Mg

d)

0.82 mol Mg

3.

How many moles are in 3.01 x 1022 atoms of magnesium?

a)

0.05 moles

b)

1.81 x 1046 moles

c)

5.00 x 1021 moles

d)

5.00 moles

4.

What is the percent composition by mass of sulfur (S) in the compound MgSO4?

a)

20.22%

b)

19.85%

c)

26.64%

d)

28.64%

5.

Determine the mass of 4.20 moles of C6H12

a)

354 g

b)

84 g

c)

337 g

d)

421 g

6.
What is the molar mass of PbSO4
a)
303.3 g/mol
b)
294.7g/mol
c)
163.8g/mol
d)
372g/mol
7.

How many grams are in 1.2 moles of Neon?

a)

0.05 grams

b)

16.6 grams

c)

21.2 grams

d)

24 grams

8.

How many hydrogen atoms are in one formula unit of C2H4O2?

a)

2

b)

1

c)

4

d)

6

9.

Use the given the chemical equation to answer the following question:

2C2H6 + O2 → 4CO2 + 6H2O


What does the number 4 represent for the formula unit 4CO2 ?

a)

The number 4 represents the coefficient, which is also equal to the number of grams of the formula unit above.

b)

The number 4 represents the subscript, which is also equal to the number of moles of the formula unit above.

c)

The number 4 represents the coefficient, which is also equal to the number of moles of the formula unit above.

d)

The number 4 represents the subscript, which is also equal to the number of grams of the formula unit above.

10.

How many grams of NH3 would result in 8 moles of NH3. What does the the number 8 do to the molar mass of the compound?

a)

The number 8 is added to the molar mass to give 25 g/mol.

b)

The number 8 multiplies the molar mass by 8 to give 136 g/mol.

c)

The number 8 divides the molar mass by 8 to give 2.13 g/mol.

d)

The number 8 does not change the molar mass of the compound.

11.

Which of the following methods should be used in order to calculate the molar mass of magnesium hydroxide?

a)

Add the masses of two moles Mg to the mass of one mole OH

b)

Add the total protons and neutrons.

c)

Add the masses of one mole Mg to the mass of one mole OH

d)

Add the masses of one mole Mg to the masses of two moles of OH.

12.

Find the number of molecules in 1.75 moles of Cu metal.

a)

1.0535x1024

b)

1.05x1025

c)

1.05x1024

d)

10.54x1023

13.

Find the number of moles in 4.95x1024 Ne atoms.

a)

8

b)

0.822

c)

8.22

d)

8.22x1046

14.

How many atoms are present in a formula unit of Fe2(CrO4)3 ?

a)

5

b)

3

c)

17

d)

13

15.

Find the molar mass of CO2 in grams, with four significant figures.

a)

44.01 g

b)

28.01 g

c)

22.00 g

d)

44 g

16.

Find the number of moles of nitrogen molecules in 55.0 liters of pure nitrogen gas, at standard temperature and pressure.

a)

2.46 moles

b)

0.407 moles

c)

3.31x1025 moles

d)

4.92 moles

17.

Octane has a formula of C8H18. Find the percent composition of carbon by weight in octane.

a)

84%

b)

528%

c)

5.28%

d)

30%

18.
What is Avagadro's Number?
a)
602,000
b)
23 x 106
c)
10 x 1023
d)
6.02 x 1023
19.
What is the equation for calculating percent composition?
a)
mass of element/mass of compound = x 100
b)
mass of compound/mass of element = x 100 
c)
total mass/molar mass = x 100 
d)
molar mass/molar mass = x 100 
20.
How many moles of argon atoms are present in 11.2 L of argon gas at STP?
a)
250.88 mol Ar
b)
0.500 mol Ar
c)
2 mol Ar
d)
1 mol Ar
21.

A chemical reaction produces 0.37 mol of N2 gas. What volume will that gas occupy at STP?

a)

0.02 L

b)

10.4 L

c)

5.2 L

d)

8.3 L

22.
How many grams are in 3.3 mol of Potassium sulfide (K2S)?
a)
360 g
b)
454 g
c)
238 g
d)
132 g
23.

Convert 86.235 g of diphosphorus pentaoxide to moles.

a)

12240 moles

b)

1.8747 moles

c)

.608 moles

d)

.60755 moles

24.
How many molecules of sugar (C6H12O6) are in a mole?
a)
24 molecules
b)
180 molecules
c)
180 g
d)
6.02 x 1023 molecules
25.
How many molecules are in 2.5 mol of NaCl?
a)
1.51x1023
b)
146
c)
4.15
d)
1.51x1024
26.
What are the units for molar mass?
a)
grams
b)
amu
c)
grams/mole
d)
liters
27.
What is the mass of 0.89 mol of CaCl2?
a)
111 grams
b)
0.008 grams
c)
98.9 grams
d)
none of the choices
28.
What is the percent by mass of oxygen in MgO?
a)
20%
b)
40%
c)
50%
d)
60%