Unit 4 Review: Chemical Reactions

Writing Formulas

Writing (unbalanced) Equations from Words

Balancing Equations

Types of Reactions

Predicting Products

100

What is the formula for elemental strontium?

100

Write the unbalanced chemical equation with state symbols:

Sodium metals reacts with oxygen gas to make solid sodium oxide.

Na(s) + O₂(g) --> Na₂O(s)

100

Balance this equation:

__K + __MgBr --> __KBr + __Mg

1 1 1 1

K + MgBr --> KBr + Mg

Already balanced! :)

100

What type of reaction is this?

Fe₂(SO₄)₃ + 6KOH --> 3K₂SO₄ + 2Fe(OH)₃

Double Replacement

100

CuCl₃ will decompose into its two elements. Finish writing the equation:

CuCl₃-->

CuCl₃--> Cu + Cl₂

elemental copper is monoatomic, elemental chlorine is diatomic

200

What is the formula for elemental iodine?

I₂

200

Write the unbalanced chemical equation with state symbols:

Copper metal reacts with crystalized strontium sulfide to produce solid copper (I) sulfide and strontium metal.

Cu(s) + SrS(s) --> Cu₂S(s) + Sr(s)

200

Balance this equation:

__FeCl₃ + __NaOH --> __Fe(OH)₃ + __NaCl

1 3 1 3

FeCl₃ + 3 NaOH --> Fe(OH)₃ + 3 NaCl

200

What type of reaction is this?

4KClO₃ --> 3KClO₄ + KCl

Decomposition

1 thing --> 2 things

200

Finish this synthesis equation:

Sulfur, oxygen and sodium react to form sodium sulfate.

S₈ + O₂ + Na -->

S₈+ O₂ + Na --> Na₂SO₄

Na goes 1st in formula because cations go 1st

300

What is the formula for barium bromide?

Charges: Ba²⁺ Br^1- need 1:2 ratio

Formula: BaBr₂

300

Fluorine gas reacts with aqueous rubidium chloride to for aqueous rubidium fluoride and chlorine gas.

F₂(g) + RbCl(aq) --> RbF(aq) + Cl₂(g)

300

Balance this equation:

__H₂SO₄ + __NaNO₂ --> __HNO₂ + __Na₂SO₄

1 2 2 1

H₂SO₄ + 2 NaNO₂ --> 2 HNO₂ + Na₂SO₄

300

What type of reaction is this?

2Mg + O₂ --> 2MgO

Synthesis

2 things --> 1 thing

300

Predict the products of this single replacement reaction:

NaBr + Cl₂ -->

NaBr + Cl₂ --> NaCl + Br₂

anions replace anions

400

What is the formula for niobium (IV) oxide?

Charges: Nb⁴⁺ O^2- need 1:2 ratio

Formula: NbO₂

400

Methane gas (CH₄) reacts with oxygen gas and produces steam and carbon dioxide.

CH₄(g) + O₂(g) --> H₂O(g) + CO₂

*you need to know the formula for carbon dioxide because that's a product for combustion reactions.

400

Balance this equation:

__C₇H₆O₂ + __O₂ --> __CO₂ + __H₂O

2 15 14 6

2 C₇H₆O₂ + 15 O₂ --> 14 CO₂ + 6 H₂O

400

What type of reaction is this?

Zn + 2HCl --> ZnCl₂ + H₂

Single Replacement

cations replace cations

400

Finish writing this combustion reaction when C₇H₁₆O is the fuel:

C₇H₁₆O

C₇H₁₆O + O₂ --> CO₂ + H₂O

You just have to know:

- O₂ is a reactant

- CO₂ and H₂O are products

of combustion

500

What is the formula for calcium phosphate?

Charge: Ca²⁺ PO₄^3- need 3:2 ratio

Formula: Ca₃(PO₄)₂

500

Zinc (I) carbonate is in a solution with aluminum nitrate. They react to form solid aluminum carbonate and aqueous zinc (I) nitrate.

Zn₂CO₃(aq) + Al(NO₃)₃(aq) --> Al₂(CO₃)₃(s) + ZnNO₃(aq)

500

Balance this equation:

__Cu₂S + __HNO₃ --> __Cu(NO₃)₂ + __CuSO₄ + __NO₂ + __H₂O

1 12 1 1 10 6

Cu₂S + 12 HNO₃ --> Cu(NO₃)₂ + CuSO₄ + 10 NO₂ + 6 H₂O

(500 level questions are hard)

500

What type of reaction is this?

C₃H₈O + O₂ --> H₂O + CO₂

C₃H₈O + O₂ --> H₂O + CO₂

Combustion

fuel and oxygen make water and carbon dioxide

500

Finish writing the products of this double replacement reaction:

CuMnO₄ + FeCl_{2 -->}

CuMnO₄ + FeCl₂ --> CuCl + Fe(MnO₄)₂

Ions: Cu¹⁺ MnO4^1- Fe²⁺ Cl^1-