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Molarity and Reactions and Productions of a Balanced Equation

1.) What is the molarity of a solution made by dissolving 25.6 g of KOH (5601 g/mol) in enough water to make 3.00 L of solution?

2.) 2 Fe + 3 Cl2 ------> 2FeCl3

How many moles of Fe are needed to produce 76.4 g of FeCl3 (162.3 g/mol)?

How many grams of Fe (55.8 g/mol) are needed to react with 123 g or cl2 (71.0 g/mol)?

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1) Molarity is concentration of the solution. It is defined as number of moles of (in this case) KOH per 1 L of solution. (C=n/V)

So, to solve your first problem, we must find the number of moles of KOH in 25.6g of KOH. It can be done using the good old n=m/M equation:

n(KOH) = 25.6g/56.1g/mol = 0.45 mol

Now we know that 25.6g of KOH actually contain 0.45 mol of KOH. The volume of solution is 3L and it is easy to ...

Solution Summary

This solution provides a step-by-step explanation in 344 words regarding the definition of molarity, how to calculate molarity of a solution and reading and balancing chemical equations.