# Molarity question

#### geffman1

1. The problem statement, all variables and given/known data
hey i really cant do this question, can anyone help. A mixture was made from solutions of sodium sulfate and aluminium sulfate.
311 mL of 0.500 M Na2SO4 solution and 190 mL of 0.300 M Al2(SO4)3 solution were mixed together. Calculate the concentration of SO42- ions in the final solution?

anyhelp would be appreciated. thanks

3. The attempt at a solution

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#### symbolipoint

Homework Helper
Gold Member
How many moles of Na2SO4 ? How many moles of SO4 does each mole of the salt have?

How many moles of Al2(SO4)3 ? How many moles of Sulfate does each mole of this salt have?

#### geffman1

moles of Naso4=0.1555
moles of Al(So4)3=0.057

How do i work out the number of moles of So4 ions?

#### Borek

Mentor
Al2(SO4)3 - how many Al3+ per molecule? How many SO42- per molecule?

Al2(SO4)3 - how many moles Al3+ per mole of salt?

#### geffman1

2 Al /molecule 3 SO4molecule.
im not sure if this is right--mole of al=26.98/(26.98x2)+(3x32.02)+(12x16)=0.0788mol???

#### Borek

Mentor
No, no need for molar masses.

Mole is just an ovegrown dozen.

If there is one exhaust in car, how many exhausts in dozen cars?

If there is one exhaust in car, how many exhausts in mole of cars?

"Molarity question"

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