Posted by **Fai** on Friday, November 23, 2012 at 3:12pm.

A 0.682g sample of impure Na2hco3 yield a solid residue consisting of nahco3 and other solid a mass of 0.467g. What was the mass percent of nac03in sample.

I do not understand I want you step by step. Clear explain for me.

nahco3 = 84

n22hco3 = 106

- chemistry -
**DrBob222**, Friday, November 23, 2012 at 3:24pm
You still have too many typos.

If the problem is this.

A 0.682 g sample of impure NaHCO3 yield a solid residue consisting of Na2CO3 and other solid with a mass of 0.467 g. What was the mass percent of NaHCO3?

Let x = mass NaHCO3.

and y = mass of the impurity.

That's two unknowns; therefore, you must have two equations and solve them simultaneously.

--------------------------

The first equation is

x + y = 0.682

The second equation is

mass Na2CO3 + mass impurity = 0.467g.

mass Na2CO3 = (x*molar mass Na2CO3/2*molar mass NaHCO3). Therefore, the two equations that must be solved are

x + y = 0.672

(106x/2*84) + y = 0.467

After you find x (which is mass NaHCO3), then

%NaHCO3 = (mass NaHCO3/mass sample(*100 = ?

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