# Weight help: 1. - Help.com

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## 1.

How many ml of 0.50M KOH is needed to react completely with 60.0ml of 0.250M FeCl2 solution to percipitate Fe(OH)?

2. A reaction is carried out between 200ml of 0.12M Pb(NO3)2 and 3.0g Zn. Calculate the mass of Pb(s) produced.

3. A mixture consists of 50.0ml of 0.10M H2SO4 and 50.0ml of 0.30M Ba(OH)2. Calculate the mass of solid produced.

4. How many grams of Epsom Salt (MgSo4•7 H2O) arr needed to react completely with 100.0ml of 0.100M BaXl2 solution?

5. A mixture is prepared by adding 20.0ml of 0.200m Na3PO4 to 30.0ml of 0.150M Ca(NO3)2.
A) what weight of Ca3(PO4)2 will be formed?
B) what will be the concentrations of each of the ions in the mixture after reaction?

I really need help with my chemistry ASAP!!

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help, i will give, not the full working and answers for you.

the 1st q:

xKOH + yFeCl2 = zFe(OH) + what?

get this step and ill help with the next. x,y and z are numbers just in case you wern’t sure.

2koh + fecl -> fe(oh)2 + 2kcl

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so its a ratio of 2:1 Koh to FeCl.

you have a .50M soln of KOH, and 0.25M FeCl.

got the first answer now on how many ml KOH are needed?

120ml KOH..?

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close, but not quite.
Therefore the volume is the same.

start all of these questions by working out the reactions , including the ratios to make them equal on both sides.

Q2 - you first need to convert the zinc into mol’s, instead of weight.
Then you work out the equation.
after that, use the ratio of pure lead to total lead (divide the pure lead by the total amount of lead to get this) then multiply this by the mol’s of lead you have (0.12 molar X 0.2litres). you can then convert the mol’s of pure lead into a weight.

Q3 - Not sure on how to explain this one, or even be sure i can do it correctly - its been 6 years since I had to do this.

Q4 - work out the equation first, then find the mass of 0.01mols of this (0.1litre X 0.1M soln)

sorry im unable to help with 5 either. I feel i could probably work it out myself, but it would take a long time and i need to get some sleep now. Hope my notes above helped you, and thanks for reminding me so much of my old chemistry knowledge :D

Thankyou for the help :D!!!!!

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