Crack DAT G-Chem Question

[V9UCSD]

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Hi guys, I have a question from the Crack DAT G-Chem test #1.

How much Na2CO3 is needed to prepare 250mL(N/10) Na2CO3?

From the explanation, I didn't understand why the gram equivalent for Na2CO3 was only 53 rather than 106, so my answer was off.

Thanks in advance! 🙂

 

[lala05]

N

Hi guys, I have a question from the Crack DAT G-Chem test #1.

How much Na2CO3 is needed to prepare 250mL(N/10) Na2CO3?

From the explanation, I didn't understand why the gram equivalent for Na2CO3 was only 53 rather than 106, so my answer was off.

Thanks in advance! 🙂

Na2CO3 breaks down into 2Na+ ions ( Na2CO3 --> 2Na+ + CO3- ), therefore it's normality is 2 (since there are 2Na+ ions for one Na2CO3). You have to divide 106 g/mol by its normality of 2 to get the gram equivalent, which equals 53 g.

 

[iamgosu]

N

Na2CO3 breaks down into 2Na+ ions ( Na2CO3 --> 2Na+ + CO3- ), therefore it's normality is 2 (since there are 2Na+ ions for one Na2CO3). You have to divide 106 g/mol by its normality of 2 to get the gram equivalent, which equals 53 g.

Yep, and it's actually CO3 (2-), and Normality always wants either +1 or -1 charge. Carbonate can absorb 2 protons, so you also have to divide by 2, which is similar to what lala05 said