The diagram shows a strip of magnesium and a strip of copper in the same beaker of dilute acid, not touching. Bubbles form far more on one strip. On which s...
Question 1 Report
The diagram shows a strip of magnesium and a strip of copper in the same beaker of dilute acid, not touching. Bubbles form far more on one strip. On which strip do more bubbles form, and why?
Answer Details
Both strips sit in the same acid at the same temperature, and they are not touching, so each behaves independently. The only variable is the metal, which makes this a fair comparison of reactivity.
Magnesium is well above hydrogen in the reactivity series, so it readily gives electrons to \( \text{H}^{+} \) ions and hydrogen streams off its surface: \( \text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2 \). Copper is below hydrogen, so it cannot displace hydrogen at all and stays unchanged. Far more bubbles therefore form on the magnesium because it is the more reactive metal.
Density has nothing to do with it, and sharing one beaker of acid does not equalise the rates, since each metal reacts at its own speed with the acid it touches.
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