How many grams of water will be produced when 14.9 L of H2 reacts according to the following equation? H2 + O2 H2O

2moles of H2 will react with 1mole of O2 to form 1 mole of water

If H2 is 14.9

O2 will be 14.9×2=29.8

The column for time decreases steadily

Explanation:

The rate of reaction depends on concentration of species, we also know that concentration decreases when more volume of water is added. Hence the concentration of the solute (thiosulphate) increases with decreasing volume of water.

As the concentration of the thiosulphate increases, reactant particles collide more frequently, the number of effective collisions between reactant particles increases and the rate of reaction increases alongside.

As the rate of reaction increases, the cross takes a shorter time to disappear because the reaction now proceeds faster. This implies that the last column (time) will decrease steadily.