Homework Help: Chemistry

Posted by Mark on Saturday, January 22, 2011 at 5:10pm.

In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B

2A ---> 3B

How many molecules of substance B are produced when 27.9 g of substance A reacts? the molar mass of substance A is 24.7 g/mol

STEP 1: convert the mass of A to moles

this is what i did :

2mol x 27.9g/24.7g = 2.259109 mol
is it right?

STEP 2 :convert the number of moles of A to the number of moles of B

STEP 3: convert the number of moles of B to molecules of B

Chemistry - Lindsey, Saturday, January 22, 2011 at 5:50pm
Step 1:
You shouldn't multiply by the 2 yet. You will use that in the next step of the problem.

Step 2: Here you will take the moles you got and use the given moles of substance.
1.1296 molA * (3 molB/2 molA)
That will give you the correct number of moles B.

Step 3: Here you use Avogadro's # to find molecules of B.

NOTE: I am not a tutor but I have done problems like this before.

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