Question

How many moles of NaOH are present in 26,5 mL of 0.190 M NaOH?

Answer 1

`"0.00504 mol"`.

Explanation:

`"0.190 M"` `NaOH` means that, for every `1` liter of `NaOH`, there will be `0.190` moles:

`"0.190 mol"/"1L"`

So, using this ratio, we can find how many moles of `NaOH` there are in `"26.5 mL"`, or `"0.0265 L"`:

`"0.190 mol"/"1L" = "0.190 × 0.0265 mol"/"0.0265 L" = "0.00504 mol"/"0.0265 L"`

Answer 2

0.00504

Explanation:

Concentration = moles of solute / volume of solution.

`sf(c=n/v)`

`:.` `sf(n=cxxv)`

`:.` `sf(n_(NaOH)=0.0190xx26.5/1000=0.00504)`

2 points to note:

1. I have converted ml to litre by dividing by 1000.

2. I have rounded to 3 sig. figs since the volume is given to this significance.