Which metal would you expect to generate more gas when exposed to a weakly acidic solution, K or Ca?
I say K because it only needs to lose one electron. Is this true?
That sounds about right. K is more unstable, and reacts more readily.
Wouldn't the amount of gas generated depend upon the AMOUNT of K or Ca used? And when you say more H2 gas, is that more volume or more mass?
On a mol basis, Ca generates 1 mol H2 gas per 1 mol Ca used while K generates 1 mol H2 gas per 2 mols K used.
The equations are (HA is a weak acid).
2K + 2HA ==> 2KA + H2
Ca + 2HA ==> CaA2 + H2.
You need to calculate the amount of H2 gas for the same mass of K vs Ca.
To determine which metal would generate more gas when exposed to a weakly acidic solution, we need to consider their reactivity with acids. Reactivity depends on factors such as the metal's position in the periodic table and its ability to lose electrons easily.
In general, alkali metals are more reactive than alkaline earth metals. Potassium (K) belongs to the alkali metal group, while calcium (Ca) belongs to the alkaline earth metal group. Alkali metals are more reactive because they have a single valence electron that is far from the nucleus, making it easier to remove.
So, your statement that potassium only needs to lose one electron is correct. This means that potassium is more likely to react with the acid and generate gas in the process compared to calcium. Therefore, K would be expected to generate more gas when exposed to a weakly acidic solution than Ca.