Chemistry Kinetics

Excess magnesium powder was added to a beaker containing hydrochloric acid, HCl (aq). The mass of the beaker and its contents was recorded and plotted against time (line I). Which change could give line II?

• Doubling the mass of powdered Mg

• Using the same mass of Mg ribbon

• Increasing the temperature

• Using the same volume of more concentrated HCl

Tags

NGSS.HS-PS1-5

Why does copper affect the reaction?

• Decreases the activation energy

• Increases the activation energy

• Increases the enthalpy change

• Decreases the enthalpy change

100 cm³ of 10% hydrogen peroxide solution decomposes at 298 K to form water and oxygen.
H₂O₂(aq) → H₂O(l) + O₂(g)
The dotted line graph represents the volume of oxygen produced.
Which graph represents the decomposition of an equal volume of a 20% solution under the same conditions?

• A

• B

• C

• D

Tags

NGSS.HS-PS1-5

Which change does not increase the initial rate of reaction when CaCO₃(s) is added to excess HCl(aq)?

• Decrease in the size of the CaCO₃(s) particles

• Increase in the temperature of the reaction mixture

• Increase in the concentration of HCl(aq), keeping the same volume

• Increase in the volume of HCl(aq), keeping the same concentration

Tags

NGSS.HS-PS1-5

Which conditions must be met for a reaction to take place?

• I and II only

• I and III only

• II and III only

• I, II and III

Tags

NGSS.HS-PS1-5

Which experimental methods could be used to observe the progress of the following reaction? Cr₂O₇^2-(aq) + 6I^-(aq) + 14H⁺(aq) → 2Cr³⁺(aq) + 3I₂(aq) + 7H₂O(l)

• I and II only

• I and III only

• II and III only

• I, II and III

Tags

NGSS.HS-PS1-5

Graph 1 shows a plot of volume of CO₂ (g) against time for the reaction of CaCO₃ (s) with 1.00 moldm⁻³ HCl (aq). The acid is the limiting reagent and entirely covers the lumps of CaCO₃ (s). Which set of conditions is most likely to give the data plotted in graph 2 when the same mass of CaCO₃ (s) is reacted with the same volume of HCl (aq) at the same temperature?

• Size of lumps - LARGER; Concentration of Acid mol/L - 1.00

• Size of lumps - SMALLER; Concentration of Acid mol/L - 0.05

• Size of lumps - SMALLER; Concentration of Acid mol/L - 1.00

• Size of lumps - LARGER; Concentration of Acid mol/L - 0.05

Tags

NGSS.HS-PS1-5

Which is a correct unit for expressing the rate of a reaction?

• mol dm^-3 s^-1

• mol dm^-3 s

• mol s

• mol^-1 dm³ s^-1

Tags

NGSS.HS-PS1-5

100cm³ of a 1.00 mol dm^-3 solution of hydrochloric acid is added to 2.00 g of small pieces of calcium carbonate at 20 °C. The volume of carbon dioxide produced against time is plotted to give curve P. Which change will produce curve Q, given that calcium carbonate is always the limiting reagent?

• Increasing the volume of the hydrochloric acid to 200 cm³

• Increasing the mass of calcium carbonate to 4.00 g

• Increasing the concentration of the hydrochloric acid to 2.00 mol dm^-3

• Replacing the 2.00 g of small pieces of calcium carbonate with 2.00 g of larger pieces of calcium carbonate

Tags

NGSS.HS-PS1-5

Which quantity can be changed by the use of a catalyst?

• I and II only

• I and III only

• II and III only

• I, II and III

Tags

NGSS.HS-PS1-5