# Help please with this chemistry molar calculation

• Chemistry
• TheePhysicsStudent
TheePhysicsStudent
Homework Statement
I was practising questions from a book printed in the 1980s, and I'm unsure where I went wrong with this Q, the answer is 68.2%
Relevant Equations
I dont use equations for chemistry mole calculations, i just think my way through it so I don't know
The question

My Working:

In your initial hand-written equation, you have “##NaHCO_3 \cdot Na_2CO_3##. This means you have implicitly assumed that you are starting with equal (molar) amounts of ##NaHCO_3## and ##Na_2CO_3##. It goes wrong from there.

Suppose the 0.500g of reactant contains x grams of ##NaHCO_3## and y grams, of ##Na_2CO_3##.

Can you set up 2 simultaneous equations for x and y and solve them?

Edit: ask for hints if you can't!

Last edited:
TheePhysicsStudent
1 dm^3 = 1000 cc, so 15 cc of the acid solution contains ?? moles of HCl?

TheePhysicsStudent
Maybe this could reassure you or maybe not:
1 decimeter is 10 centimeters.
(careful! these two lines have a mistake.)
0.100 mole/(dm^3) * (10/1)^3(dm/cm)^3

100 mole/(cm)^3

------------------------------------
THAT above is obviously wrong. This is the kind of trouble I have when I do things strictly through keyboard and computer screen. My work later using pen and paper was bettter.

Should have that been like so:
0.100 (moles/dm^3)*(1/10)(dm/cm)(1/10)(dm/cm)(1/10)(dm/cm)
0.100(1/1000)(moles/cm^3)
0.000100 moles per cubic centimeter

Last edited:
TheePhysicsStudent
symbolipoint said:
Maybe this could reassure you or maybe not:
1 decimeter is 10 centimeters.

0.100 mole/(dm^3) * (10/1)^3(dm/cm)^3

100 mole/(cm)^3
0.1 mole/1000cc=##0.0001\ moles/cc##

TheePhysicsStudent

Replies
7
Views
4K
Replies
2
Views
2K
Replies
6
Views
2K
Replies
4
Views
594
Replies
1
Views
3K
Replies
13
Views
3K
Replies
2
Views
3K
Replies
4
Views
1K
Replies
1
Views
1K
Replies
11
Views
3K