Physical Science Chapter 7 Review

Which of the following changes will decrease the rate of a chemical reaction?

• increasing the temperature

• grinding a reactant into a fine powder

• stirring the reaction mixture

• decreasing the concentration of one of the reactants

A reaction rate is the rate at which reactants change into products over time

• True

• false

Tags

NGSS.HS-PS1-5

In a chemical reaction that is at equilibrium, which of the following is true?

• All of the reactants have been converted to products

• The reaction stops even though some reactants remain

• Forward and reverse reactions occur at the same rate

• All of the products are gases

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NGSS.HS-PS1-6

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In the chemical reaction below, how could you shift the equilibrium toward water?

2H₂ (g) + O₂ (g) <--> 2H₂O (g) + heat

• increase the temperature

• increase the pressure

• decrease the amount of oxygen

• add steam to the mixture

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NGSS.HS-PS1-5

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During a chemical reaction, an input of energy is always required to

• break chemical bonds in a molecule

• build chemical bonds as a molecule forms

• separate products from reactants

• change reactants to the liquid phase so they can react

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NGSS.HS-PS1-4

In an exothermic reaction, the total chemical energy of the products added to the energy released by the reactions is

• less than the energy of the reactants

• equal to the chemical energy of the reactants

• greater than the chemical energy of the reactants

• not related to the chemical energy of the reactants

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NGSS.MS-PS3-4

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Combustion is always an exothermic reaction

• true

• false

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NGSS.MS-PS1-4

Which of the following is a balanced chemical equation for the reaction of aluminum and ammonium perchlorate?

• Al + NH₄ClO₄ —› Al₂O₃ + NH₄Cl

• 4Al + 3NH₄ClO₄ —› 4Al₂O₃  + 3NH₄Cl

• 8Al + NH₄ClO₄ —› 4Al₂O₃ + NH₄Cl

• 8Al + 3NH₄ClO₄ —› 4Al₂O₃ + 3NH₄Cl

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NGSS.MS-PS1-2

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How many moles of NaCl (molar mass = 58.5) are there in a 10-gram sample?

• 58 mol

• 5.8 mol

• 0.17 mol

• 0.28 mol

In the reaction shown below, how many grams of hydrogen are produced when 10 moles of potassium react with water?

2K + 2H₂O —› 2KOH + H₂

• 2.5 g

• 5 g

• 10 g

• 20 g

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NGSS.MS-PS1-2

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