University of Maine

Problem 66

Reactants $A$ and $B$ form product $C .$ Draw a road map and write a Plan to find the mass (g) of $C$ when 25 g of A reacts with excess $B$

Answer

1) Find the limiting reactant. In this case since it is stated that we have reactant $\mathrm{B}$ in excess that means that $\mathrm{A}$ is our limiting reactant.

2) We calculate the moles of the limiting reactant.

3) From stochiometry we get the moles of the product, C.

4) We multiply the moles with molecular mass (Mr).

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## Discussion

## Video Transcript

in strict geometric calculations. It's useful to create a roadmap to describe how to go from one quantity to another. So if, for example, we have 25 grams of a an excess amount of be reacts to form, see, we can calculate how much C should form in grants. The idea that something's in excess means that the only quantity that determines our product is the initial amount of a. So if we have a mass that we start out with 25 grams, the first thing that we need to do is to change that two moles of a and we do that by dividing by the molar mass of A A. Once we have moles of a we confined walls of C. We do that using the mole ratio from the balanced equation and the last step. Once you know your moles of See, we can change it to grams of C using the molar mass of C. And this time we multiply. So using the road map, it sets up your calculation for how to convert from one quantity to another. In a chemical reaction

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\begin{equation}

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Ti(s) + 2 F2(g)-TiF4(s)

a. 5.0 g Ti, 5.0 g F2

b. 2.4 g Ti, 1.6 g F2

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Calculate G for this reaction at 25 C under the following conditions: