Free Printable Moles, Percent Comp, Formulas Review

1.

What percentage of the total atomic mass of carbon monoxide (CO) is composed of carbon?

a)

29%

b)

43%

c)

57%

d)

73%

2.

What is the molar mass of table salt (NaCl)?

a)

116.886 g/mol

b)

35.453 g/mol

c)

22.990 g/mol

d)

58.443 g/mol

3.

What is the molar mass of NaOH?

a)

40 g/mol

b)

38.989 g/mol

c)

23.998 g/mol

d)

57.004 g/mol

4.

How to calculate molar mass of H₂O?

a)

2+16=18

b)

1+16=17

c)

2+32=34

d)

1+31=32

5.

Which list of number of atoms in Mg(NO₃)₂ is right?

a)

Mg : 1--NO : 6

b)

Mg : 1-- N : 6--O: 6

c)

Mg : 1-- N: 1-- O: 5

d)

Mg : 1-- N: 2-- O: 6

6.

What is the percent by mass of chlorine in NaCl?

a)

39%

b)

61%

c)

35%

d)

65%

7.

What is the empirical formula of a substance with the molecular formula C₂H₄?

a)

C₂H₂

b)

C₂H₂

c)

C₁H₁

d)

CH₂

8.

What is the empirical formula of a substance with the molecular formula Se₈F₁₂?

a)

Se₈F₁₂

b)

Se₂F₃

c)

Se₄F₃

d)

SeF

9.

Avery, Samuel, and Hannah are in a chemistry class. Their teacher asked them to identify the formula with the lowest whole # ratio of elements in a compound. What is this formula called?

a)

Molecular Formula

b)

Chemical Formula

c)

Empirical Formula

d)

Distance Formula

10.

Liam, Grace, and Olivia are studying chemistry together. They come across a chemical formula that shows the actual number and kinds of atoms present in one molecule of a compound. They are unsure what this is called. Can you help them identify it?

a)

ionic formula

b)

covalent formula

c)

empirical formula

d)

molecular formula

11.

Ethan is baking a cake and he sees a recipe that calls for 2H₂O. He knows that the subscript in the chemical formula represents something. What does it represent?

a)

The big number that tells you the number of cakes Ethan needs to bake.

b)

The atomic number

c)

The little number that tells the number of atoms for each element.

12.

In chemistry, a "mole" is:

a)

The mass of an atom

b)

a large number used to count particles

c)

based on the volume of a substance

13.

Which list of number of atoms in Mg(NO2)₂ is right?

a)

Mg : 1--NO : 2

b)

Mg : 1-- N : 6--O: 2

c)

Mg : 1-- N: 1-- O: 2

d)

Mg : 1-- N: 2-- O: 4

14.

The mass of one mole of an element is equal to

a)

its atomic number from the periodic table, but in amus.

b)

its atomic mass from the periodic table, but in amus.

c)

its atomic mass from the periodic table, but in grams.

d)

its atomic number from the periodic table, but in grams.

15.

What can be determined from a balanced chemical equation?

a)

Mole ratio of any two substances in the reaction

b)

Energy released in the reaction.

c)

Electron configuration of all elements in the reaction.

d)

Mechanism involved in the reaction.

16.

BALANCED chemical equations tell you the relative amounts or the ratios of reactants and products.

Use the following BALANCED chemical equation to determine the ratio:
$2HgO\ \rightarrow\ 2Hg\ +\ O_2$
What is the ratio of Hg to $O_2$

a)

2:2

b)

1:1

c)

2:1

d)

1:2

17.

BALANCED chemical equations tell you the relative amounts or the ratios of reactants and products.

Use the following BALANCED chemical equation to determine the ratio:
$2HgO\ \rightarrow\ 2Hg\ +\ O_2$
What is the ratio of HgO to $O_2$

a)

2:2

b)

1:1

c)

2:1

d)

1:2

18.

BALANCED chemical equations tell you the relative amounts or the ratios of reactants and products.

Use the following BALANCED chemical equation to determine the ratio:
$4NH_3+6NO\ \rightarrow\ 5N_2+6H_2O$
What is the ratio of $NH_3$ to $N_2$

a)

4:5

b)

1:1

c)

2:3

d)

5:6

19.

When setting up a problem using mole ratios, remember to use dimensional analysis. Start with the given. The unit that the given has needs to be on bottom in the next frame so it will cancel out. Make sure to label with both unit and chemical formula.

Using the following BALANCED chemical equation....
If I decompose 34 moles of HgO, how many moles of oxygen will I produce? What will the ratio that you use look like in this problem?

$\frac{34\ moles\ HgO}{ }\times\frac{\ \ \ \ \ ?\ \ \ \ }{?}$

a)

$\frac{1mole\ O_2}{2\ mole\ HgO}$

b)

$\frac{2\ mole\ HgO}{1\ mole\ O_2}$

c)

$\frac{2\ mole\ Hg}{1\ mole\ O_2}$

20.

When setting up a problem using mole ratios, remember to use dimensional analysis. Start with the given. The unit that the given has needs to be on bottom in the next frame so it will cancel out. Make sure to label with both unit and chemical formula.

Using the following BALANCED chemical equation.... $4NH_3+6NO\rightarrow5N_2+6H_2O$
Bacteria will cause ammonia $NH_3$ to react with NO to put nitrogen back in the air, along with water, as part of the nitrogen cycle. If there are 3.56 moles of NO in the soil, how many moles of ammonia are needed to react with it?

$\frac{3.56\ moles\ NO}{ }\times\frac{\ \ \ \ \ ?\ \ \ \ }{?}$

a)

$\frac{\ 6\ mole\ NO}{4\ mole\ NH_3}$

b)

$\frac{2\ mole\ NH_3}{3\ mole\ NO}$

c)

$\frac{6\ mole\ Hg}{5\ mole\ N_2}$

Moles, Percent Comp, Formulas Review

Total questions: 20

Worksheet time: 44mins

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