7) 14 carat gold has a purity of 58.3%. How many moles of gold are in 163 grams of 14 carat gold?

Answer in units of moles.
8) A 15.9 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 11.5 g. What was the mass of iron in the sample of ore?
Answer in units of g.
9) A 47.2 g of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 13 grams. What was the percent iron in the sample of ore?
Answer in units of %.
10) An ore contains Fe3O4 and no other iron. The iron in a 51.5-gram sample of the ore is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 22.3 g. What was the mass of Fe3O4 in the sample of ore?
Answer in units of g.

7) To find the number of moles of gold in 163 grams of 14 carat gold, we need to first calculate the amount of gold present in the 163 grams.

Since 14 carat gold has a purity of 58.3%, it means that only 58.3% of the 163 grams is actually gold.

To find the amount of gold in grams, we can use the formula:
Amount of gold = (purity/100) * weight of gold

Substituting the values:
Amount of gold = (58.3/100) * 163 grams

Now, we need to convert the amount of gold in grams to moles. To do this, we need to know the molar mass of gold, which is 196.97 g/mol.

Using the formula:
Number of moles = Amount of gold (in grams) / Molar mass of gold

Substituting the values, we get:
Number of moles = (58.3/100) * 163 grams / 196.97 g/mol

Calculating this expression will give us the answer in units of moles.

8) To find the mass of iron in the sample of ore, we need to subtract the mass of Fe2O3 from the initial mass of the ore.

Given, the mass of Fe2O3 = 11.5 grams
Therefore, the mass of iron = mass of ore - mass of Fe2O3

Substituting the values, we get:
Mass of iron = 15.9 g - 11.5 g

Calculating this expression will give us the answer in units of grams.

9) To calculate the percent iron in the sample of ore, we need to divide the mass of Fe2O3 by the mass of the ore and then multiply by 100.

Given, the mass of Fe2O3 = 13 grams and the mass of the ore = 47.2 grams

Using the formula:
Percent iron = (mass of Fe2O3 / mass of the ore) * 100

Substituting the values, we get:
Percent iron = (13 g / 47.2 g) * 100

Calculating this expression will give us the answer in units of percent.

10) To find the mass of Fe3O4 in the sample of ore, we need to first find the amount of iron (Fe) in the given mass of Fe2O3 and then use the ratio of Fe3O4 to Fe2O3 to calculate the mass.

Given, the mass of Fe2O3 = 22.3 grams and the initial mass of the ore = 51.5 grams

Using the ratio: The molar ratio between Fe2O3 and Fe3O4 is 2:3.

To find the mass of Fe3O4, we can use the formula:
Mass of Fe3O4 = (amount of Fe * molar mass of Fe3O4) / molar mass of Fe

First, we need to calculate the amount of Fe in Fe2O3. Since the molar ratio between Fe2O3 and Fe is 2:3, we can find it as follows:
Amount of Fe = (amount of Fe2O3 * 3) / 2

Next, we calculate the mass of Fe3O4 using the calculated amount of Fe and the molar masses:
Mass of Fe3O4 = (amount of Fe * molar mass of Fe3O4) / molar mass of Fe

Calculating this expression will give us the answer in units of grams.

7) 14 carat gold has a purity of 58.3%. How many moles of gold are in 163 grams of 14 carat gold?

Answer in units of moles.
g Au = 163 x 0.583 = ?
mols Au = g/atomic mass = ?


8) A 15.9 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 11.5 g. What was the mass of iron in the sample of ore?
Answer in units of g.
11.5 g Fe2O3 x (2*atomic mass Fe/molar mass Fe2O3) = ?

9) A 47.2 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 13 grams. What was the percent iron in the sample of ore?
Answer in units of %.
Follow the above to find grams Fe in the sample. Then % Fe = (g Fe/mass sample)*100 = ?

10) An ore contains Fe3O4 and no other iron. The iron in a 51.5-gram sample of the ore is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 22.3 g. What was the mass of Fe3O4 in the sample of ore?
Answer in units of g.
Follow same procedure as #8. The factor to use is (2*molar mass Fe3O4/3*molar mass Fe2O3)

Post your work if you have further questions.