Question

If a 0.489 M solution of L-ascorbic acid is being prepared what mass of solid (in grams) must be added to make a 500 ml of solution?

Answer 1

43.063 gm

Explanation:

Since molecular weight of Ascorbic acid is 176.12 gm, so to prepare 1 litre of 1M solution , 176.12 gm Ascorbic Acid is required. But to prepare 0.489 M solution 176.12 x 0.489 = 86.122 gm of Ascorbic Acid is required for 1 litre of solution. And in same way to prepare
0.5 litres solution 86.122/2 = 43.061 gm Ascorbic Acid is required.

Answer 2

`43.06 \ "g"` of Vitamin `"C"` is needed.

Explanation:

We want to make a `0.489 \ "M"` solution of L-ascorbic acid, or so-called vitamin `"C"`.

We know that `0.489 \ "M"=0.489 \ "mol/L"=0.489 \ "mol/1000 mL"`.

So, a `500 \ "mL"` solution will need to contain:

`(0.489 \ "mol")/(1000color(red)cancelcolor(black)"mL")*500color(red)cancelcolor(black)"mL"`

`=0.489 \ "mol"*1/2`

`=0.2445 \ "mol"`

So, we are going to need `0.2445` moles of L-ascorbic acid. To convert that amount into grams, we need to multiply the number of moles by the molar mass of it. The molar mass of L-ascorbic acid is `176.12 \ "g/mol"`. So here, we would need:

`0.2445color(red)cancelcolor(black)"mol"*(176.12 \ "g")/(color(red)cancelcolor(black)"mol")=43.06 \ "g"`