16 grams

2 grams

32 grams

8 grams

$$ - {{d\left[ {{H_2}} \right]} \over {dt}}$$ = $$ - {{d\left[ {{I_2}} \right]} \over {dt}}$$ = $$ - {{d\left[ {{HI}} \right]} \over {dt}}$$

$$ {{d\left[ {{H_2}} \right]} \over {dt}}$$ = $$ {{d\left[ {{I_2}} \right]} \over {dt}}$$ = $$ {{d\left[ {{HI}} \right]} \over {dt}}$$

$${1 \over 2}{{d\left[ {{H_2}} \right]} \over {dt}}$$ = $${1 \over 2}{{d\left[ {{I_2}} \right]} \over {dt}}$$ = $$ - {{d\left[ {{HI}} \right]} \over {dt}}$$

$$ - 2{{d\left[ {{H_2}} \right]} \over {dt}}$$ = $$ - 2{{d\left[ {{I_2}} \right]} \over {dt}}$$ = $${{d\left[ {{HI}} \right]} \over {dt}}$$