Lakeland Chemical Reactions Review

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Given the unbalanced equation: __Fe2O3 + __CO →__Fe + __CO2When the equation is correctly balanced using the smallest whole-number coefficients, what is the coefficient of CO?A) 1 B) 2

C) 3 D) 4

Question 1

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• Try to balance the O atoms to get the correct coefficient

Correct!

• The balanced equation is:Fe2O3 + 3CO 2Fe + 3CO2

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Which of these metals will react most readily with 1.0 M HCl toproduce H2(g)?

A) Ca B) Mg

C) K D) Zn

Question 2

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• Use the Activity Series for Metals on your periodic table to decide which metal is the most active

Correct!

• Potassium is the most active metal on the activity series, so it will most readily replace hydrogen in HCl

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When a neutral atom undergoes oxidation, theatom’s oxidation state

A) Decrease as it gains electrons B) Decrease as it loses electrons

C) Increase as it gains electrons D) Increase as it loses electrons

Question 3

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• LEO says GER. Oxidation state is another name for charge

Correct!

• As a substance loses electrons its oxidation state becomes more positive

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In which compound does chlorine have thehighest oxidation number?

A) NaClO4 B) NaClO3

C) NaClO2 D) NaClO

Question 4

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• You are looking for the charge of chlorine. Use the charge of Na and O to solve for the charge of chlorine.

Correct!

• In NaClO4 chlorine must have a charge of 7+

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Which equation represents a double replacementreaction?

A) 2 Na + 2 H2O → 2 NaOH + H2 B) CaCO3 → CaO + CO2

C) LiOH + HCl → LiCl + H2O D) CH4 + 2 O2 → CO2 + 2 H2O

Question 5

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• A double replacement is two compounds reacting to form two new compounds

Correct!

• LiOH + HCl LiCl + H2O is two compounds reacting to form two new compounds

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In most aqueous reactions as temperature decreases, the effectiveness of collisions between reacting particles

A) increases B) decreases

C) Remains the same D) Impossible to tell

Question 6

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• As the temperature decreases molecules slow down

Correct!

• As temperature decreases molecules slow down and therefore do not collide as often

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Given the reaction: Cu(s) + 4HNO3(aq) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O(_)As the reaction occurs, what happens to copper?

A) It undergoes reduction and its oxidation number decreases.

B) It undergoes reduction and its oxidation number increases.

C) It undergoes oxidation and its oxidation number decreases.

D) It undergoes oxidation and its oxidation number increases.

Question 7

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• Compare the charge of copper when it is by itself as a reactant and a cation in Cu(NO3)2 as a product

Correct!

• Copper has a charge of 0 as a reactant and a charge of +2 as a product. An increase in charge occurs as electrons are lost which is oxidation.

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The activation energy required for a chemicalreaction can be decreased by

A) increasing the surface area of the reactant

B) adding a catalyst to the reaction

C) increasing the temperature of the reactant

D) adding more reactant

Question 8

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• Temperature, surface area and concentration all change the speed of reaction by changing the amount of collisions

Correct!

• A catalyst reduces the amount of activation energy needed to start a reaction

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Which expression correctly represents a balancedreduction half-reaction?

A) Na+ + e– → Na B) Na → Na+ + e–

C) Cl2 + 2e– → Cl– D) 2Cl– → Cl2 + 2e–

Question 9

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• Reduction is a gain of electrons. Make sure that both charge and number of atoms are balanced.

Correct!

• Na+ + e- Na shows both a gain of electrons and is balanced with charge and number of atoms

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In which substance does phosphorus have a+3 oxidation state?

A) P4O10 B) PCl5

C) Ca3(PO4)2 D) KH2PO3

Question 10

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• Use the charges of the other atoms to determine the charge of P in each compound

Correct!

• In KH2PO3 K and H have a charge of +1 and O has a charge of -2. To end up with a balanced compound, P must have a charge of +3

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Given the unbalanced equation: ____N2(g) + ____O2(g) -->__N2O5(g) When the equation is balanced using smallest whole numbers, the coefficient of N2(g) will be

A) 1 B) 2

C) 4 D) 5

Question 11

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• Make sure that you have equal number of both N and O

Correct!

• The balanced equation is 2N2 + 5O2 2N2O5

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In the presence of excess oxygen, hydrocarbonsburn completely to form water and

A) C B) CO

C) CO2 D) CO3

Question 12

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• A hydrocarbon and oxygen reacting is a combustion reaction.

Correct!

• A hydrocarbon and oxygen will always react to form water and carbon dioxide (CO2)

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What is the correct balanced equation for lithium and nitrogen produce lithium nitride

A) Li + N LiN B) 6 Li + N2 2 Li3N

C) 3 Li + N Li3N D) Li + N2 LiN2

Question 13

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• Nitrogen is a diatomic element. Remember to use the charges for the ions in order to put lithium and nitrogen together.

Correct!

• Lithium (Li) and nitrogen (N2) produce lithium nitride (Li3N) according to the equation 6 Li + N2 2 Li3N

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The reactants side of the chemical equation of zinc and hydrochloric acid is shown below:

Zn + 2HCl ?

Which of the following represents the products of this reaction?

A) ZnH2 + Cl2 B) 2 ZnCl + 2H

C) ZnCl2 + H2 D) ZnCl + H2

Question 14

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• Zinc is a metal so it should replace the cation in HCl since this is a single replacement reaction.

Correct!

• Zinc replaces Hydrogen according to the equation: Zn + 2HCl ZnCl2 + H2

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The reactants side of the chemical equation of copper (II) chloride and sodium hydroxide is shown below:

CuCl2 + 2 NaOH ?

Which of the following represents the products of this reaction?

A) Cu(OH)2 + 2 NaCl B) CuNa2 + 2ClOH

C) NaCl + CuOH D) NaCu + OHCl

Question 15

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• Double replacements follow the pattern:AB + CD AD + CB

Correct!

• The balanced equation is: CuCl2 + 2NaOH 2 NaCl + Cu(OH)2

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