A solution is made by mixing 90.6 g of magnesium sulfate heptahydrate with 2320.0 g of water.

690.00 mL of the solution has a mass of 745.20 g.
What is the molarity of the magnesium sulfate solution?

mols MgSO4.7H2O = 90.6g/molar mass MgSO4.7H2O

density solution = g/mL = (2320+90.6)/690 = about 1.08 but you should be more careful.
v = mass/density = (2320+90.6)/1.08 = ?mL and convert to L then
M = mols/L solution.

I made typos galore here. The density is g/mL =

density = mass/volume = 745.2g/690 mL = 1.08 g/mL and not the numbers I showed. The density of 1.08 g/mL; however, is correct. The rest of the problem looks ok to me.

To find the molarity of the magnesium sulfate solution, we need to calculate the number of moles of magnesium sulfate in the solution and then divide it by the volume of the solution in liters.

Step 1: Find the number of moles of magnesium sulfate (MgSO4)

First, we need to convert the given mass of magnesium sulfate heptahydrate (MgSO4·7H2O) to the mass of pure magnesium sulfate (MgSO4).

The molar mass of MgSO4·7H2O can be calculated as follows:
Molar mass of Mg = 24.31 g/mol
Molar mass of S = 32.07 g/mol
Molar mass of O = 16.00 g/mol
Molar mass of H = 1.01 g/mol

Molar mass of MgSO4·7H2O = (24.31 g/mol) + (32.07 g/mol) + (4 × 16.00 g/mol) + (7 × 2 × 1.01 g/mol)
= 120.38 g/mol

Given mass of MgSO4·7H2O = 90.6 g

Now we can calculate the moles of MgSO4 as follows:
Moles of MgSO4 = (Given mass of MgSO4·7H2O) / (Molar mass of MgSO4·7H2O)
= 90.6 g / 120.38 g/mol

Step 2: Find the volume of the solution in liters

Given mass of the solution = 745.20 g
Density of water = 1.00 g/mL (since water has a density of 1.00 g/cm³, which is equivalent to 1.00 g/mL)
Volume of the solution = (Given mass of the solution) / (Density of water)
= 745.20 g / 1.00 g/mL
= 745.20 mL

Step 3: Convert the volume of the solution to liters

Molarity is defined as moles of solute per liter of solution. Therefore, we need to convert the volume of the solution from milliliters to liters.

Volume of the solution in liters = (Volume of the solution in mL) / 1000 mL/L
= 745.20 mL / 1000 mL/L

Step 4: Calculate the molarity of the magnesium sulfate solution

Molarity = (Moles of MgSO4) / (Volume of the solution in liters)
= (90.6 g / 120.38 g/mol) / (745.20 mL / 1000 mL/L)

Now you can substitute the values and calculate the molarity of the magnesium sulfate solution.