A 100mL volume of 2.0molL1 hydrochloric acid titrated a sample of metal carbonate. What is the equivalent weight of the metal?

3 Answers
Feb 16, 2017

The equivalent weight of the metal is 100.0gmol1

Explanation:

First we need a chemical equation:

MCO3(s)+2HCl(aq)MCl2(aq)+H2O(l)+CO2(g)

Moles of HCl=0.100L×2molL1=0.200mol

Given the equation, the metal carbonate represents 0.100mol, and thus, given the equation, the equivalent weight of the metal carbonate is 100.0gmol1. This equivalent weight is CONSISTENT with a formula of CaCO3.

Oct 21, 2017

Equivalent weight of metal is 20 g/eq

Explanation:

For HCl
Molarity = Normality

Gram equivalents of HCl = Normality × Volume in litres
=2N×100×103L
=0.2 eq

For complete neutralisation
Gram equivalents of HCl = Gram equivalents of metal carbonate

Equivalent weight of metal carbonate =Weight of metal carbonateGram equivalents of metal carbonate

=10g0.2eq=50 g/eq

Equivalent weight of carbonate (CO23)=12+(3×16)2=30 g/eq

Equivalent weight of metal carbonate = Equivalent weight of metal + Equivalent weight of carbonate

50 g/eq = x + 30 g/eq
x = 20 g/eq

∴ Equivalent weight of metal is 20 g/eq

Oct 21, 2017

The number of moles of HCL reacted with Carbonate salt is

=molarity of acid× volume of acid in L

=2mol/L×0.1L=0.2mol

So the mass of HCl reacted =0.2×36.5g, where molar mass of HCl=36.5g/mol

Now we know from the law of equivalent proportion that the ratio of masses of two reacting substances for neutralization is equal to the ratio of their equivalent masses.

Hence we can say

Equivalent mass of metal carboateEquivalent mas of HCl=Reacting mass of metal carboateEquivalent mas of HCl

Equivalent mass of metal (x=?)+ equivalent mass of CO23Equivalent mas of HCl=0.2×36.536.5

x+30g/equiv36.5g/equiv=10g0.2×36.5g

x=20g/equiv

Please note
Equivalent mass of CO23= formula mass of CO23valency

=12+3×162=30g/equiv