Reaction Stoichiometry

Balancing Equations

100

Balance the equation:
___H₂ + ___O₂ --> ___H₂O

2H₂ + O₂ --> 2H₂O

200

Predict the products and balance:

Synthesis

___Mg + ___O₂ --> ________________

2Mg + O₂ --> 2MgO

300

Predict the products and balance:

Double replacement

___NaCl + ___CaF₂ --> ______________________

2NaCl + CaF₂ --> CaCl₂ + 2NaF

400

Write and balance an equation:

Combustion of dicarbon tetrahydride.

C₂H₄ + 3O₂ --> 2CO₂ + 2H₂O

500

Write and balance an equation:

Single replacement reaction between zinc (II) oxide and sodium.

ZnO + 2Na --> Na₂O + Zn

The Mole Concept

100

Magnesium bromide is a ___________ (ionic or covalent) compound and has ____________ (atoms, formula units, or molecules) as its representative particles.

Ionic, formula units

200

One mole of oxygen gas at STP has a volume of _____________ L

22.4 L

300

One mole of Calcium fluoride has a mass of ___________ grams.

CaF₂

Ca: 40g x 1 = 40g
F: 19g x 2 = 38g

78 grams

400

One mole of Magnesium bromide contains ______________ representative particles and ___________atoms

MgBr₂

6.02x10²³ r.p.
1.806x10²⁴ atoms

500

The percent composition by mass of each element in C₂H₃O₂ is:

_____ % C
_____ % H
_____ % O

C: 12g x 2 = 24g
H: 1g x 3 = 3g
O: 16g x 2 = 32g


total mass= 59 g

%C = 24g/59g = 41% C
%H = 3g/59g = 5% H
%O = 32g/59g = 54% O

Molar Conversions

100

What is the volume of 2 moles of hydrogen gas at STP?

2 moles H₂ x 22.4L/1mole = 44.8 L

200

How many moles of sodium chloride are there in 1.204x10²⁴ formula units?

1.204x10²⁴ r.p. NaCl x 1mole/6.02x10²³r.p. = 2 moles

300

What is the mass of 3 moles of carbon dioxide?

3 mol CO₂ x 44g/1mol = 132g

C: 12g x 1 = 12g
O: 16g x 2 = 32g

400

What is the volume of 40 grams of water vapor (gas form of water) at STP?

40 g H₂O x 1mole/18g x 22.4L/1mole = 49.8 L

H: 1g x 2 = 2g
O: 16g x 1 = 16g

500

How many atoms are there in 56g of carbon monoxide?

56g CO x 1mol/28g x 6.02x10²³r.p/1mole x 2atoms/1r.p. = 2.408x10²⁴

Stoichiometry

100

For the following reaction:

2H₂ + O₂ --> 2H₂O

If you start with 64 grams oxygen gas, how many moles of water will be produced?

64g O₂ x 1mole/32g x 2mol H₂O/1mol O₂ = 4 mol H₂O

200

For the following reaction:

2NaCl + F₂ --> 2NaF + Cl₂

If you start with 4 moles of sodium chloride, what volume of chlorine gas will be produced at STP?

4mol NaCl x 1mol Cl₂/2mol NaCl x 22.4L/1mol = 44.8 L Cl₂

300

2H₂O --> 2H₂ + O₂

If you start with 18g of water, how many r.p.s of hydrogen gas will be produced?

2H₂O --> 2H₂ + O₂

18g H₂O x 1mol/18g x 2mol H₂/2mol H₂O x 6.02x10²³r.p./1mol = 6.02x10²³r.p. H₂

400

Balance the following combustion equation and then solve the stoichiometry problem:

___C₃H₄ + ___O₂ --> ___CO₂ + ___H₂O

Given: 3 moles CO₂
Unknown: ? g H₂O

C₃H₄ + 3O₂ --> 3CO₂ + 2H₂O

3mol CO₂ x 2mol H₂O/ 3mol CO₂ x 18g/1mol = 36g H₂O

500

___MgO + ___S --> ___MgS + ___O₂
Balance the equation and do the stoichiometry problem below:
If the reaction starts with 16g sulfur, how many grams of the compound product will be produced?

2MgO + 2S --> 2MgS + O₂

16g S x 1mol/32g x 2mol MgS/ 2mol S x 56g/1mol = 28g MgS

mass MgS Mg: 24g x 1 = 24g S: 32g x 1 = 32g total= 56 g