If 4.57 grams of AgBr was isolated in a gravimetric analysis of a 9.30 gram sample, what is the % Br- by weight in the samples?

please provide steps to get to answer

What is the mass of Br?

moles AgBr = 4.57 grams AgBr x (1 mol AgBr/molar mass AgBr).

There is 1 mole Br in 1 mole AgBr; therefore, you now have moles Br.

How many grams Br do you have?
grams Br = moles Br x atomic mass Br

What percent is that of the original sample?
%Br = (grams Br/mass sample)*100 = ??

1.94%

To find the percentage of Br- by weight in the sample, we need to determine the amount of Br- present in the 9.30 gram sample.

Step 1: Calculate the moles of AgBr
First, we will convert the mass of AgBr to moles using its molar mass. The molar mass of AgBr is the sum of the atomic masses of silver (Ag) and bromine (Br). It can be calculated as follows:

AgBr: Ag (silver) has a molar mass of 107.87 g/mol, and Br (bromine) has a molar mass of 79.90 g/mol.
The molar mass of AgBr = (1 * 107.87 g/mol) + (1 * 79.90 g/mol) = 187.77 g/mol

Using the mass of AgBr (4.57 g) and its molar mass (187.77 g/mol), we can calculate the number of moles:
moles of AgBr = mass / molar mass = 4.57 g / 187.77 g/mol

Step 2: Calculate the moles of Br-
In AgBr, there is one bromine ion (Br-) for every AgBr molecule. Therefore, the number of moles of bromine (Br-) is the same as the number of moles of AgBr.

moles of Br- = moles of AgBr

Step 3: Calculate the mass of Br-
To find the mass of Br- in the sample (9.30 g), we multiply the moles of Br- by its molar mass:

mass of Br- = moles of Br- * molar mass of Br-
mass of Br- = moles of AgBr * molar mass of Br-

Step 4: Calculate the percentage of Br- by weight in the sample
Finally, we calculate the percentage of Br- in the sample by dividing the mass of Br- by the mass of the sample (9.30 g) and multiplying by 100:

% Br- = (mass of Br- / mass of sample) * 100

By applying these steps, you should be able to calculate the percentage of Br- by weight in the sample.