A mixture of 5.00 g of sodium carbonate, Na2CO3 and sodium hydrogen carbonate, NaHCO3 is heated. The loss in mass is 0.31 g. Sodium carbonate does not decompose on heating. Calculate the percentage by mass of sodium carbonate in the mixture.

I saw the question and it’s answer its 83.2%

I might argue with you that Na2CO3 does not decompose on heating but for this problem we will assume that is true.

2NaHCO3 ==> Na2CO3 + H2O + CO2

I don't see how to do with other than two simultaneous equations.
Let X = g NaHCO3
and Y = g Na2CO3
-----------------
eqn 1 is X + Y = 5.00

Then you want to convert X to loss in mass due to CO2 and H2O.
mm = molar mass

(X/mm NaHCO3)*)1/2)*mmCO2 = g loss CO2
(X/mm NaHCO3)*(1/2)*mmH2O = g loss H2O
Add those together to get total loss which is 0.31g; i.e.,
[(X/mm NaHCO3)*(1/2)*44] + [X/mm NaHCO3)*(1/2)*18 = 0.31 and solve this equation for X Plug that into equation 1 to find Na2CO3.
Then %Na2CO3 = (g Na2CO2/5.00)*100 = ?

Post your work if you get stuck.

Na2co3 doesn't decompose

From the equation of reaction;
168g of NaHco3-->6g of [co2+H2O]
x------->0.31g
x=0.84g
Mass of Na2co3=5-0.84=4.16g

%by mass of Na2co3=[4.16/5]×100
=83.2%

Oh, chemistry, the world of magical transformations! Let's dive right into it, shall we?

Alright, so let's start with the given information: we have a mixture of sodium carbonate (Na2CO3) and sodium hydrogen carbonate (NaHCO3), and when it's heated, there's a loss in mass of 0.31 g.

Now, since sodium carbonate doesn't decompose on heating (too stubborn, I guess), the loss in mass can be attributed to the decomposition of sodium hydrogen carbonate. Poor thing couldn't handle the heat!

To find the percentage by mass of sodium carbonate, we need to first calculate the mass of sodium hydrogen carbonate that was lost. So the mass of sodium hydrogen carbonate lost is 0.31 g.

Next, we need to determine the initial mass of the mixture. The initial mass of the mixture can be calculated by adding the mass of sodium carbonate and sodium hydrogen carbonate. Unfortunately, the question doesn't give us the individual masses of each compound, so we'll need to be a little creative here.

But don't worry, I've got a plan! Let's assume that the mixture contains x grams of sodium carbonate. Since the total mass of the mixture is 5.00 g, the mass of sodium hydrogen carbonate would be (5.00 - x) grams.

Now, when we heat the mixture, the sodium hydrogen carbonate decomposes, and we lose 0.31 g. So the final mass of the mixture would be (5.00 - 0.31) g.

Since sodium carbonate doesn't decompose, the final mass would be the mass of sodium carbonate remaining, which is x grams.

Putting it all together, we have the equation: x = (5.00 - 0.31) g.

Solving that equation, we find that x is approximately 4.69 g.

So, the mass of sodium carbonate in the mixture is 4.69 g. To calculate the percentage by mass, we divide the mass of sodium carbonate by the initial mass of the mixture (5.00 g) and multiply by 100.

Therefore, the percentage by mass of sodium carbonate in the mixture is roughly 4.69 g / 5.00 g * 100, which is about 93.8%.

So, approximately 93.8% of the mixture is sodium carbonate. It seems like sodium carbonate is the queen of the mixture!

To calculate the percentage by mass of sodium carbonate in the mixture, we need to know the moles of sodium carbonate and the total moles of both sodium carbonate and sodium hydrogen carbonate.

Step 1: Calculate the moles of sodium carbonate (Na2CO3)
To calculate the moles, we use the formula:
moles = mass / molar mass

The molar mass of sodium carbonate (Na2CO3) is:
(2 x atomic mass of sodium) + atomic mass of carbon + (3 x atomic mass of oxygen)
= (2 x 22.99 g/mol) + 12.01 g/mol + (3 x 16.00 g/mol)
= 105.99 g/mol

Now we can calculate the moles of sodium carbonate:
moles of Na2CO3 = 5.00 g / 105.99 g/mol

Step 2: Calculate the moles of sodium hydrogen carbonate (NaHCO3)
To calculate the moles, we use the same formula:
moles = mass / molar mass

The molar mass of sodium hydrogen carbonate (NaHCO3) is:
atomic mass of sodium + atomic mass of hydrogen + atomic mass of carbon + (3 x atomic mass of oxygen)
= 22.99 g/mol + 1.01 g/mol + 12.01 g/mol + (3 x 16.00 g/mol)
= 84.01 g/mol

Now we can calculate the moles of sodium hydrogen carbonate:
moles of NaHCO3 = (5.00 g - 0.31 g) / 84.01 g/mol
(We subtract the loss in mass, 0.31 g, because it comes from the decomposition of sodium hydrogen carbonate.)

Step 3: Calculate the total moles of both compounds
Total moles = moles of Na2CO3 + moles of NaHCO3

Step 4: Calculate the percentage by mass of sodium carbonate
Percentage by mass of sodium carbonate = (moles of Na2CO3 / total moles) x 100

Now you can perform the calculations to find the answer.