[kaywalker]

For example in the first order reaction: H2O2 --> H2O + 1/2 O2
even though there is only half mole of O2 we don't have to multiply everything by 2, to find rate of reaction.

so I am confused, when do we actually have to have integers for every single molecule, multiply all molecules by a factor, and include the stoichiometric coefficient in this formula?
When do we leave it as it is?
I don't understand when we have to pay attention to stoichiometric coefficients and when we don't.

Thanks in advance

[Arkcon]

There's no reason we can't use fractional coefficients in a properly balanced chemical equation.  I think, if it's easy to reach whole numbers, we should try, especially if the whole number is one, so we can leave it blank as it is understood.  Therefore:

H₂O₂ --> H₂O + 1/2 O₂

is neater than

2 H₂O₂ --> 2 H₂O + O₂

there are fewer numbers to muddy your handwriting.  At some level, balancing chemical equations is just an exercice in least common denominators.

[kaywalker]

For example in the first order reaction: H2O2 --> H2O + 1/2 O2
even though there is only half mole of O2 we don't have to multiply everything by 2, to find rate of reaction.

so I am confused, when do we actually have to have integers for every single molecule, multiply all molecules by a factor, and include the stoichiometric coefficient in this formula?
When do we leave it as it is?
I don't understand when we have to pay attention to stoichiometric coefficients and when we don't.

Thanks in advance

thanks for the response. so when asked what the rate of reaction is, which one do we base it on? not in this particular case but say you have the fallowing:

2A + B --> 3C + 4D

which reactant/product do we base our calculations on?

[enahs]

The real answer to the question is; ask your teacher. Ultimately it makes no difference. However, some teachers are sticklers for having no fractions. If your teacher says no fractions, no fractions.

[Yggdrasil]

In general, the rate of a chemical reaction is defined as the change in concentration of a reactant/product divided by that species's stoichiometric coefficient.  So in the case of the reaction:

2A + B --> 3C + 4D

The rate is defined as:

Rate = -(1/2)d[A]/dt = -d[B ]/dt = (1/3)d[C]/dt = (1/4)d[D]/dt

[kaywalker]

thanks guys.