Question

75.
The mass percentage of sodium carbonate is 4% If 5g of sodium carbonate is
present in 120 g of water. Then mass percentage of water is
1) 24%
2) 25%
3) 96%
4) 30%
​

Answer 1

BE BRAINLY ⚡

Formula: Na2CO3

Na Molecular Mass: 22.98 grams

C Molecular Mass= 12.01 grams

O Molecular Mass= 16 grams

Now, the molecular mass of the compound: 2(22.98) + 12.01 + 3(16)= 105.97 grams

Now, when you do percent composition all you are doing is this: Amount of Element in Grams/ Total Compound Mass in Grams x 100%.

So, lets do that for each of these elements:

Na: 105.97 /2×22.98 ×100%=43.37%

C: 105.97 /12.01 ×100%=11.33%

O: 105.97/3×16 ×100%=45.30%

Now, add up these percentages and make sure that they add up to exactly 100%.

Now, add up these percentages and make sure that they add up to exactly 100%.43.37% + 11.33% + 45.30%= 100.00 %

Answer 2

Answer:

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