Chemistry · Unit 2 · Rates of chemical reactions · Rates of reactions
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A student investigates the reaction between zinc metal and hydrochloric acid by conducting four experiments. Each experiment uses 50 mL of 1.0 mol L\(^{-1}\) HCl at 25°C, but varies the physical form of 2.0 g of zinc: powdered zinc in experiment 1, zinc granules in experiment 2, a single zinc strip in experiment 3, and zinc filings in experiment 4. Which experiment will produce hydrogen gas at the fastest initial rate?
Magnesium ribbon reacts with dilute hydrochloric acid according to the equation: \( \text{Mg}(s) + 2\text{HCl}(aq) \rightarrow \text{MgCl}_2(aq) + \text{H}_2(g) \) Explain how cutting the magnesium ribbon into smaller pieces would affect the rate of this reaction.
A student investigates the decomposition of hydrogen peroxide \((\text{H}_2\text{O}_2)\) in aqueous solution. The student observes that when manganese dioxide \((\text{MnO}_2)\) powder is added to the hydrogen peroxide solution, oxygen gas is produced more rapidly than without the powder. After the reaction is complete, the manganese dioxide is recovered unchanged. The manganese dioxide increases the rate of decomposition because it