Unit 9 Review

Unit 9 Review

• ​Feel free to skip any videos ONLY IF you already know how to solve the problems.

• If you get stuck, watch the videos before moving on to the next slide to work out the problems.

• Look at the Unit 9 Notes tab on Canvas for the powerpoint presentations.

Types of Chemical Reactions

Match

Match the following equations to their type.

• 2H₂ + O₂ → 2H₂O

• 2HgO → Hg + O₂

• K + ZnCl₂ → KCl + Zn

• K₂CO₃ + BaCl₂  → 2KCl + BaCO₃ 

• CH₄ + 2O₂ → CO₂ + H₂O

Synthesis

Decomposition

Single - Replacement

Double - Replacement

Combustion

• Synthesis

• Decomposition

• Single - Replacement

• Double - Replacement

• Combustion

• Must follow the law of conservation of mass: mass cannot be created nor destroyed.

• Reactants = Products

Balancing Chemical Equations

Labelling

Work out the problem as shown in the previous video.

Drag the following coefficients so they balance out the equation.

Drag labels to their correct position on the image

2

4

3

Multiple Choice

_BaCl₂ + _Na₂SO₄ → _NaCl + _BaSO₄

• balanced

• 4, 3, 1

• 2,2,4,3

• 1, 1, 2, 1

●Shows the relationship between any two substances in balanced chemical equations

●Obtained from the coefficients of a balanced chemical equation.

​

Mole to Mole Ratio

Multiple Choice

2Al₂O₃ --> 4Al + 3O₂ What is the mole ratio of aluminum, to oxygen (O₂)?

• 2:4

• 2:3

• 4:3

• 3:2

Multiple Choice

N₂ +  3H₂ −->  2NH₃
How many moles of hydrogen are needed to react with 2 moles of nitrogen?

• 1

• 3

• 6

• 5

Multiple Choice

2 KClO₃ → 2 KCl + 3 O₂
How many moles of oxygen are produced when 6.7 moles of KClO₃ decompose completely?

• 6.7 mol

• 10.05 mol

• 1.0 mol

• 4.5 mol

Fill in the Blanks

Molar mass- mass of one mole
► For an element, molar mass is also the average atomic mass

(found on periodic table)

► For a compound, molar mass is the sum of average atomic mass of each atom present in the compound

​EX: H₂O

H- 1g x 2mol = 2g

O- 16g x 1mol =16g

-

H₂O = 18g/mol

Grams to Mol

Multiple Choice

How do I move from grams to moles?

• multiply by molar mass

• divide by molar mass

• multiply by Avogadro's number

• divide by Avogadro's number

Multiple Choice

If 25.0 mol of calcium hydroxide (MM 74g/mol) are mixed with excess sodium how many grams of sodium hydroxide (NaOH) (MM 40g/mol)will be produced?

Sodium and calcium hydroxide react according to the equation below:

2Na + 1Ca(OH)₂ -> 2NaOH  + 1Ca 

• 2000g

• 500g

• 925g

• 3700g

​Percent Yield

• Actual yield - the amount of product measured in the laboratory.

  Sometimes called “experimental yield”

• Theoretical yield - the amount of product predicted (through calculations) to be produced. 

Multiple Choice

Use the answer from the previous section:

If 25.0 mol of calcium hydroxide (MM 74g/mol) are mixed with excess sodium how many grams of NaOH could be expected to be produced? (2000g)

Determine the percent yield if 987 grams of NaOH (MM 40g/mol) were experimentally produced?

• 26.68%

• 202.63%

• 49.35%

• 374.87%

Grams to Grams