# Chem

posted by .

As a part of a study to see whther just the chloride ion on NaCl accelerates the rusting of iron, a student decided to see whtjer iron rusted in a solution on Na2SO4. The solution was made by dissolving 4.550 g of Na2SO4 in water using 125.0 mL volumetric flask to adjust the final volume. What is the molarity of the solution?

I don't understand this question at all. What do you do with the iron :S

• Chem -

Actually, the question isn't stated very well but what they mean is that 4.550 g Na2SO4 are dissolved in a total volume of 125 mL. They want you to calculate the molarity. To do this, just remember the definition of molarity. It is the number of moles per liter of solution.
So you use 4.550 g Na2SO4, calculate the moles in that mass, then moles/L (the L is 0.125 ) gives the molarity.

• Chem -

mass = 4.550 g
molar mass = 142.05 g/mol
n= 0.032030975 mol
c= 0.032030975/0.125 = 0.256 mol/L

would I have 3 or 4 sig. digs? cause when I converted 125.0mL into 0.125 L I lost a sig dig;or should it be 0.1250 L?

• Chem -

You have 4 s.f. in 4.550.
There are 6 s.f. in 142.043 which I used instead of 142.05).
There are 4 s.f. in 125.0 mL (or 0.1250).
Therefore, you are allowed 4 s.f. (from the lowest which is 0.1250 or 4.550) so the answer is 0.25626 moles/L which rounds to 0.2563 M to 4 s.f. [I take issue, somewhat, that you lose one place when converting 125.0 to 0.1250. I see 4 s.f. in both 125.0 as well as in 0.1250.]

• Chem -

Thank you so much :)

## Similar Questions

1. ### chemistry

write the formula for and indicate the charge on each of the following ions: a) sodium ion b) aluminum ion c) chloride ion d) nitride ion e e)iron (II) ion f) iron (III) ion
2. ### chem

In the reaction of hydrogen peroxide with iron (II) ion in acidic solution to form iron (III) ion and water, the oxidizing agent is____. Is it hydrogen peroxide?
3. ### chem

How many electrons are transferred in the reaction of hydrogen peroxide with iron (II) ion in acidic solution to form iron (III) ion and water
4. ### Chemistry

Suppose you want a mixture that contains 2.5 grams of iron ion and three times as many moles of oxalate ion as moles of iron. If the iron comes from iron(iii)chloride and the oxalate ion from K2C2O4, how many grams of each of the compounds …
5. ### Chemistry e

The rusting of iron is represented by the equation 4Fe +3O2 --> 2Fe2O3. If you have a 1.50-mol sample of iron, how many moles of Fe2O3 will there be after the iron has rusted completely?
6. ### chemistry(rusting)

Why metal(eg. iron)placed at aqueous solution will be more easily occur rusting?
7. ### chemistry

The rusting of iron is represented by the equation 4Fe + 3O2 2Fe2O3. If you have a 1.75-mol sample of iron, how many moles of Fe2O3 will there be after the iron has rusted completely?
8. ### Chem 1010

Determine the molarity of a solution made by dissolving 13.8 g of sodium chloride in enough water to make 750.0 mL of solution. (The MM of NaCl is 58.44 g/mol)
9. ### chemistry

in an experiment, a 4.000grams sample of aluminum metal is added to a solution containing 5.000grams of dissolved iron chloride. the reaction results in the formation of aluminum chloride and metallic iron. when the reaction is complete, …
10. ### Chemistry

A student determines the iron (II) content of a solution by first precipitating it as iron (II) hydroxide, and then decomposing the hydroxide to iron (II) oxide by heating. How many grams of iron (II) oxide should the student obtain …

More Similar Questions