Heating 1.124g of an unknown NaHCO3-NaCl mixture resulted ina mass loss of 0.270g.
1) Calculate the mass of NaHCO3 present in the original mixture.
2) Calculate the mass percent of NaHCO3 in the uknown mixture
2NaHCO3 + heat ==> Na2CO3 + H2O + CO2
I would set this up like this.
Let X = mass NaHCO3
and Y = mass NaCl
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g NaHCO3 + g NaCl = 1.124 and
g Na2CO3 + g NaCl = 1.124 - 0.270
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X + Y = 1.124
X(1 mol Na2CO3/1 mols NaHCO3) + Y = 0.854
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X + Y = 1.124
X(106/2*84) + Y = 0.854
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X + Y = 1.124
0.631X + Y = 0.854
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Solve these two equation simultaneously for X. That will give you grams NaHCO3. You should look up the molar masses of Na2CO3 and NaHCO3 and use a little more accuracy that my rounded numbers of 106 and 84.
After you find g NaHCO3, then
%NaHCO3 = (mass NaHCO3/mass sample)*100 = ??
My numbers are 0.732 g NaHCO3 for 65.1% which should be close.
thank you
1) Well, if we subtract the mass loss from the original mass, we can find the mass of the remaining mixture. So, from 1.124g, if we subtract 0.270g, we will be left with a mixture mass of... (drumroll please)... 0.854g!
2) Now, to calculate the mass percent of NaHCO3, we need to know the mass of NaHCO3 in the mixture. To do this, we'll use a little math magic. The mass loss of 0.270g is due to the decomposition of NaHCO3, so that means the mass of NaHCO3 in the mixture is also 0.270g.
Now, we just need to divide the mass of NaHCO3 by the mass of the original mixture and multiply by 100 to get the mass percent. So, (0.270g / 1.124g) * 100 = 24.11%.
Therefore, the mass percent of NaHCO3 in the unknown mixture is approximately 24.11%.
To solve these problems, we need to understand the concepts of stoichiometry and mass percent in chemistry. Here's how you can solve each question:
1) Calculate the mass of NaHCO3 present in the original mixture:
- First, we need to find out the mass of the NaHCO3 that was lost during the heating process.
- Given that the mass loss is 0.270g, we can assume that this mass loss is only due to the decomposition of NaHCO3, and there is no mass loss from NaCl.
- Therefore, the mass loss of 0.270g is equal to the mass of NaHCO3.
- So, the mass of NaHCO3 present in the mixture is 0.270g.
2) Calculate the mass percent of NaHCO3 in the unknown mixture:
- The mass percent is a measure of the amount of a component in a mixture, expressed as a percentage of the total mass of the mixture.
- To calculate the mass percent of NaHCO3, we need to determine the total mass of the unknown mixture.
- We already know the mass of NaHCO3 from the previous calculation, which is 0.270g.
- To find the mass percent, we divide the mass of NaHCO3 by the total mass of the mixture and multiply by 100 to get a percentage.
For example, if the total mass of the unknown mixture is 2.5g:
Mass percent of NaHCO3 = (0.270g / 2.5g) x 100 = 10.8%
Remember, to solve these problems accurately, you need to have precise measurements of mass, know the composition of the unknown mixture, and assume that the mass loss is due only to the decomposition of NaHCO3.