[ritu29]

look here it is

the whole thing

1 set up burette fill with acid
2 use pipette to transfer 25.00cm3 of the 0..100M sodium hydroxide to 250cm3 conical flask
3 add 2-3 drops of phenol red indicator to conical flask to make pink colour

4 add acid from burette to flask until colour change

5 obtain 2 concordent resultsright so i have done all this....

i have obtained 2 concordent results...found the No of moles of NaOH and from that i have found the molarity of acid

now i have to is

Q: the concentration of the acid solution is 7.50g per dm3. calculate the relative formula mass of acidhow do i do that???

plz help....

[Borek]

You should know molar concentration from the practical part. What's the definition of molar concentration?

[ritu29]

plz give me the solution ....plz

[Borek]

Write definition of molar concentration.

[ritu29]

Write definition of molar concentration.

u mean molar mass...

its the mass of one mole of a substance...the units are grams mol-1

[Borek]

No, I mean molar concentration.

[ritu29]

No, I mean molar concentration.

Molar concentration is a measure of the concentration of a solution. It is defined as moles of solute per liter of solvent, and has units of mol dm-3.


 Cx=nX divideed by V    nX is amount of x      V is volume and Cx is the concentration of sol

[Borek]

Molar concentration is a measure of the concentration of a solution. It is defined as moles of solute per liter of solvent, and has units of mol dm-3.

Cx=nX divideed by V    nX is amount of x      V is volume and Cx is the concentration of sol

OK. You know the concentration Can you calculate number of moles per liter of acid solution?

[ritu29]

OK. You know the concentration Can you calculate number of moles per liter of acid solution?

do u use the No of moles = vol x con divided by 1000 formula?

but first i have to convert the concentration from grams dm3 to liters ...do i have to divide that by 4 to do that?

[Borek]

Molar concentration is a thing you have determined in your practical part. You should be able to calculate number of moles per liter and you know what is a mass of acid dissolved per liter. That's all you need to find out molar mass.

[ritu29]

Molar concentration is a thing you have determined in your practical part. You should be able to calculate number of moles per liter and you know what is a mass of acid dissolved per liter. That's all you need to find out molar mass.

hey so is it like i convert the 7.50g dm3 into cm3

like 7.50 divide 1000= 0.0075

then i use the molarity of acid i found which is 0.119

and then to find Mr =0.0075 x 1000 divide 0.199

is it this???/

but is there a formula like Mr= mass x 1000 divide concentration

plz ans

[Borek]

You have already wrote formula for molar concentration - SOLVE it for number of moles and CALCULATE how many moles of the acid is in 1L of solution.