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May 6, 2015

Homework Help: science

Posted by Josh on Sunday, March 18, 2007 at 2:37am.

Posted by Josh on Saturday, March 17, 2007 at 10:58pm.

How many grams of hydrochloric acid are required to react completely with 4.30g of zinc?

How many molecules of gas will be produced?


For Further Reading


science - DrBob222, Saturday, March 17, 2007 at 11:07pm
1. Write the balanced chemical equation.
Zn + 2HCl ==> ZnCl2 + H2

2. Convert grams Zn to mols.
mols = grams/atomic mass Zn.

3. Using the balanced equation, convert mols Zn to mols HCl.

4. Now convert mols HCl to grams HCl.
grams HCl = mols HCl x molar mass HCl.

Post your work if you get stuck.



science - Josh, Saturday, March 17, 2007 at 11:19pm
Zn=1 Zn=1
H=2 H=2
Cl=2 Cl=2

mols= 4.30/65.4
=.065749235

I dont know what to do next




science - Josh, Saturday, March 17, 2007 at 11:25pm
mol of HCl=73?



science - DrBob222, Sunday, March 18, 2007 at 12:55am
1. Write the balanced chemical equation.
Zn + 2HCl ==> ZnCl2 + H2

2. Convert grams Zn to mols.
mols = grams/atomic mass Zn.
You have 4.30/65.4 = 0.0658 mols Zn which is correct.

3. Using the balanced equation, convert mols Zn to mols HCl.
Use the coefficients in the balanced equation to convert mols Zn to mols HCl.
mols HCl = 0.0658 mols Zn x (2 mols HCl/1 mol Zn) =?? mols HCl

4. Now convert mols HCl to grams HCl.
grams HCl = mols HCl x molar mass HCl.

??mols HCl from step 3 x molar mass HCl = xx

post your work if you have trouble.



science - Jennifer, Sunday, March 18, 2007 at 1:08am
4.74



science - Josh, Sunday, March 18, 2007 at 2:00am
what is the answer for questions a and b? or have we gotten there yet?





This is crazy reposting all the work, which is repetitive.

You write the balanced equation, which you have. You determine the moles of zinc, which you have. You determine the moles of HCl it takes to react with the moles of zinc (look at the balanced equation for the ratio). Finally, convert those moles of HCL to grams of HCl.
For the molecules of gas, use the balanced equation to give you the ratio of moles H2 per mole of zinc. Then, from the ratio, and the moles of zinc, you can calculate the moles of H2. Molecules? moles of H2 times avagradros number.


see...http://members.aol.com/rtccpu/DOCs/stoich/DoubleYDiagram.PDF

1.204?

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