What is the mole fraction of NaBr in an aqueous solution that contains 20.1% NaBr (weight/weight%)?
0.0422
No one has posted the solution and correct answer so for anyone who looks this up in the future.
Assume the solution is 100g
100-20.1=79.9
20.1g of NaBr and 79.9g of H2O
the atomic mass of NaBr is 102.89 and the atomic mass of H2O is 18.016
20.1/102.89=0.1954 79.9/18.016=4.4349
to get the total weight of the solution we add NaBr to H2O
0.1954+4.4349=4.6303
now we find the weight %
0.1954/4.6303=0.0422
hope this helps any future people :)
To find the mole fraction of NaBr in the given aqueous solution, we need to understand the concept of mole fraction and how to calculate it.
Mole fraction (symbolized by χ) is a unitless quantity that represents the ratio of the number of moles of a specific component to the total number of moles in a mixture.
In order to calculate the mole fraction of NaBr, we need to know the masses of NaBr and water in the solution. From the information given in the question, we know that the solution contains 20.1% NaBr by weight.
To calculate the mole fraction, we need to follow these steps:
1. Convert the given weight percentage of NaBr to grams. Assume you have 100g of the solution, so 20.1g of that is NaBr (since 20.1% is the weight percentage).
2. Determine the moles of NaBr by dividing the mass of NaBr (step 1) by its molar mass. The molar mass of NaBr can be found by adding the atomic masses of sodium (Na) and bromine (Br) from the periodic table. The atomic mass of Na is approximately 22.99 g/mol, and the atomic mass of Br is approximately 79.90 g/mol. Therefore, the molar mass of NaBr is 22.99 g/mol + 79.90 g/mol = 102.89 g/mol.
Moles of NaBr = Mass of NaBr / Molar mass of NaBr
3. Calculate the moles of water in the solution. Since the solution contains a known mass of NaBr (20.1g), the remaining mass (100g - 20.1g) represents the mass of water.
4. Find the total moles in the solution by adding the moles of NaBr and the moles of water.
5. Calculate the mole fraction of NaBr by dividing the moles of NaBr by the total moles in the solution.
Therefore, if you follow these steps, you should be able to find the mole fraction of NaBr in the given aqueous solution that contains 20.1% NaBr (weight/weight%).
% w/w of 20.1% means 20.1 g NaBr in 100 g solution.
So g NaBr = 20.1
g solution = 100 g = g NaBr + g H2O or
g H2O = 100-20.1 = 79.9
n NaBr = grams/molar mass = ?
n H2O = grams/molar mass = ?
Total mols = n NaBr + n H2O
XNaBr = nNaBr/total mols.