I'm confused on how to set up the problem for each question..

1.) Calculate the empirical formula of a compound if a 6.21 g sample contains 1.67g of cerium and the remainder iodine

2.) An unknown compound contains 85.64% carbon with the remainder hydrogen. It has a molar mass of 42.08 g/mol. ... I don't know how to find its empirical and molecular formulas?

3.) The molar mass of benzene, an important industrial solvent, is 78.0 g/mol and its empirical formula is CH. What is the molecular formula for benzene?

see the second post you did.

First one ,

1- percentage of cerium (Z=58) 1.67/6.21 * 100% = 26.89%
2- percentage of iodine is 100- 26.89= 73.10%
Divide each of the percentage by its mass then we get
Cerium- 26.89/140=0.192
Iodine - 73.10/126.9=0.576
Out of those two numbers divide both by the lowest no. Since 0.192 is lowest
Cerium - 0.192/0.192= 1
Iodine - 0.576/0.192= 3
Therefore empirical formula is CeI3

Second one same way as first you will get

C-1
H-2
Empirical formula is CH2
Empirical formula mass is 14u
Molar mass is 42.08u
Divide molar mass by empirical formula mass and you'll get n value. N=3
Multiply N to empirical formula to get molecular formula which is C3H6 (propene)

To set up the problem for each question, you will need to use the concept of empirical and molecular formulas, as well as the given information.

1.) Calculate the empirical formula of a compound if a 6.21 g sample contains 1.67g of cerium and the remainder iodine.

To set up the problem, you need to determine the ratio of cerium to iodine in the compound.

First, calculate the number of moles of cerium and iodine using their respective masses and their molar masses. The molar mass of cerium (Ce) is 140.12 g/mol, and the molar mass of iodine (I) is 126.90 g/mol.

Moles of cerium = mass of cerium / molar mass of cerium
Moles of iodine = (total mass - mass of cerium) / molar mass of iodine

Next, divide the moles of each element by the smallest number of moles obtained.

Divide the moles of cerium and iodine by the smallest mole value to get the mole ratio. This ratio represents the empirical formula.

Finally, write the empirical formula using the mole ratio. If the result is close to a whole number, round it to the nearest whole number. Otherwise, multiply by a whole number to get a whole number ratio.

2.) An unknown compound contains 85.64% carbon with the remainder hydrogen. It has a molar mass of 42.08 g/mol. How do I find its empirical and molecular formulas?

To find the empirical formula, you need to determine the ratio of carbon to hydrogen in the compound.

First, assume you have 100g of the compound. Then, convert the percentages into grams.

Next, calculate the number of moles of carbon and hydrogen using their respective masses and molar masses. The molar mass of carbon (C) is 12.01 g/mol, and the molar mass of hydrogen (H) is 1.01 g/mol.

Moles of carbon = mass of carbon / molar mass of carbon
Moles of hydrogen = mass of hydrogen / molar mass of hydrogen

Divide the moles of each element by the smallest number of moles obtained.

Divide the moles of carbon and hydrogen by the smallest mole value to get the mole ratio. This ratio represents the empirical formula.

Finally, write the empirical formula using the mole ratio. If the result is close to a whole number, round it to the nearest whole number. Otherwise, multiply by a whole number to get a whole number ratio.

To find the molecular formula, you need the molar mass of the compound.

Calculate the empirical formula mass by summing the masses of the empirical formula's elements.

Molar mass / empirical formula mass = n

n represents the ratio between the molecular formula and empirical formula.

Multiply the subscripts in the empirical formula by n to obtain the molecular formula.

3.) The molar mass of benzene, an important industrial solvent, is 78.0 g/mol, and its empirical formula is CH. What is the molecular formula for benzene?

Here, the empirical formula is already given as CH. To find the molecular formula, you need the molar mass of the compound.

Calculate the empirical formula mass by summing the masses of the elements in the empirical formula.

Molar mass / empirical formula mass = n

n represents the ratio between the molecular formula and empirical formula.

Multiply the subscripts in the empirical formula by n to obtain the molecular formula.

In this case, the empirical formula mass of CH is 12.01 g/mol + 1.01 g/mol = 13.02 g/mol.

78.0 g/mol / 13.02 g/mol = 6

Multiply the subscripts in the empirical formula by 6:

C6H6 is the molecular formula for benzene.