Can someone help me in my chemistry homework?

Question

X is an unknown element.

40 cm³ of an acid, H2X containing 1.23 g of the acid in 250 cm³ solution is neutralized by 20 cm³ of 0.2 mol of sodium hydroxide solution. Calculate
(a) the concentration of the acid in mol/dm³;
(b) the relative molecular mass of the acid; and
(c) the relative formula of the X¬2- ion.

Correction on part (c):
(c) the relative formula mass of the X^2- ion.

Answer 1

I have not touched chemistry for years but this is my best try:

The chemical reaction is represented by:
H2X + 2NaOH -> (Na)2X + 2H2O

(a) Therefore 2M1V1 = M2V2 where
M1 = molarity of acid = unknown
V1 = volume of acid = 40 cm3
M2 = molarity of base = 0.2 mol
V2 = volume of base = 20 cm3

Solving, M1 = 0.05 mol

(b) It is stated that 1.23g of acid is present in 250cm3 solution.
Therefore one litre solution contains 4.92g (1.23 X 4) of acid.
4.92g of acid is in turn equivalent to 0.05 mol.
So 1 mol acid solution contains 98.4g (4.92 X 20) of acid.

Therefore the relative molecular mass of acid is 98.4.

(c) Since H2X = 98.4
Hence X = 98.4 - 2 = 96.4

Using trial & error, we calculate that SO4 = 96 (i.e. 32 + 4 X 16)

Therefore the formula of the X ion is SO4.

Answer 2

your avatar is cute..but i can't answer your homework..im still in my biology...