Washing soda is a hydrate of sodium carbonate. Its formula is Na2CO3 X xH20. A 2.714 g sample of washing soda is heated until a constant mass of 1.006 of Na2CO3 is reached. What is x? What is the experimental mass percent of water in the hydrate?
2.714-1.006 = 1.708 g = mass water released upon heating.
Convert grams to moles.
moles wash soda = 1.006/106 = ??
moles H2O = 1.708/18.015 = ??
Now find the ratio of the two numbers to each other. The easy way to do that is to divide the smaller number by itself (which assures you of getting 1.000 for that number). Then divide the other number by the same small number and round to a whole number. That will give you (Na2CO3)1.xH2O; i.e., x will be the number of H2O molecules in ONE mole Na2CO3.
For percent water, (grams water/grams compound)*100 = ??
3.4
To find the value of x in Na2CO3 x xH2O, we need to calculate the moles of water lost during heating.
Step 1: Calculate the moles of Na2CO3
First, find the molar mass of Na2CO3:
Na: 2 * atomic mass of Na = 2 * 22.99 g/mol = 45.98 g/mol
C: 1 * atomic mass of C = 1 * 12.01 g/mol = 12.01 g/mol
O: 3 * atomic mass of O = 3 * 16.00 g/mol = 48.00 g/mol
Molar mass of Na2CO3 = 45.98 + 12.01 + 48.00 = 105.99 g/mol
Next, calculate the moles of Na2CO3 in the 1.006 g sample:
moles of Na2CO3 = mass of Na2CO3 / molar mass of Na2CO3
moles of Na2CO3 = 1.006 g / 105.99 g/mol
Step 2: Calculate the moles of H2O
Since the sample lost water during heating, we need to calculate the difference in mass to find the moles of water lost.
Mass of water lost = mass of initial sample - mass of Na2CO3
Mass of water lost = 2.714 g - 1.006 g = 1.708 g
Next, calculate the moles of H2O in the 1.708 g sample:
moles of H2O = mass of H2O / molar mass of H2O
molar mass of H2O = 2 * atomic mass of H + atomic mass of O = 2 * 1.01 g/mol + 16.00 g/mol = 18.02 g/mol
moles of H2O = 1.708 g / 18.02 g/mol
Step 3: Find the value of x
Now, we know that the ratio of moles of Na2CO3 to moles of H2O is 1: x. We can set up an equation to solve for x.
moles of Na2CO3 / moles of H2O = 1 / x
1.006 g / 105.99 g/mol / (1.708 g / 18.02 g/mol) = 1 / x
x = (1.006 g / 105.99 g/mol) / (1.708 g / 18.02 g/mol)
x = 0.0095 mol / 0.0950 mol
x ≈ 0.10
Therefore, x in Na2CO3 x xH2O is approximately 0.10.
Step 4: Calculate the experimental mass percent of water in the hydrate
The experimental mass percent of water can be calculated by dividing the mass of water lost by the initial mass of the hydrate, and then multiplying by 100.
Experimental mass percent of water = (mass of water lost / initial mass of hydrate) * 100
Experimental mass percent of water = (1.708 g / 2.714 g) * 100
Experimental mass percent of water ≈ 62.9%
Therefore, the experimental mass percent of water in the hydrate is approximately 62.9%.
To find x, we need to calculate the mass of water lost during heating, and to find the experimental mass percent of water in the hydrate, we need to compare the mass of water lost to the total mass of the hydrate.
First, let's find the mass of water lost during heating:
Mass of washing soda (Na2CO3 X xH2O) = 2.714 g
Mass of anhydrous sodium carbonate (Na2CO3) after heating = 1.006 g
To calculate the mass of water lost, we subtract the mass of anhydrous sodium carbonate from the initial mass of washing soda:
Mass of water lost = Mass of washing soda - Mass of anhydrous sodium carbonate
= 2.714 g - 1.006 g
= 1.708 g
Now, to find x, we need to determine the number of moles of water lost and the number of moles of anhydrous sodium carbonate:
The molar mass of water (H2O) = 2 * atomic mass of hydrogen + atomic mass of oxygen
= 2 * 1 g/mol + 16 g/mol
= 18 g/mol
The molar mass of anhydrous sodium carbonate (Na2CO3) = 2 * atomic mass of sodium + atomic mass of carbon + 3 * atomic mass of oxygen
= 2 * 23 g/mol + 12 g/mol + 3 * 16 g/mol
= 106 g/mol
Now, we can calculate the number of moles of water lost:
Number of moles of water = Mass of water lost / molar mass of water
= 1.708 g / 18 g/mol
≈ 0.095 moles
Similarly, we can calculate the number of moles of anhydrous sodium carbonate:
Number of moles of sodium carbonate = Mass of anhydrous sodium carbonate / molar mass of anhydrous sodium carbonate
= 1.006 g / 106 g/mol
≈ 0.0095 moles
The ratio between the number of moles of water lost and the number of moles of anhydrous sodium carbonate gives us the value of x in the formula Na2CO3 X xH2O:
x = number of moles of water lost / number of moles of anhydrous sodium carbonate
= 0.095 moles / 0.0095 moles
= 10
Therefore, x = 10.
Now, let's calculate the experimental mass percent of water in the hydrate:
Experimental mass percent of water = (Mass of water lost / Mass of washing soda) * 100
= (1.708 g / 2.714 g) * 100
≈ 63.05%
Therefore, the experimental mass percent of water in the hydrate is approximately 63.05%.