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# Cisplatin $\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}\right],$ a compound used in cancer treatment, is prepared by reaction of ammonia with potassium tetrachloroplatinate:$$\mathrm{K}_{2} \mathrm{PtCl}_{4}+2 \mathrm{NH}_{3} \longrightarrow 2 \mathrm{KCl}+\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}$$How many grams of cisplatin are formed from $55.8 \mathrm{~g}$ of $\mathrm{K}_{2} \mathrm{PtCl}_{4}$ and $35.6 \mathrm{~g}$ of $\mathrm{NH}_{3}$ if the reaction takes place in $95 \%$ yield based on the limiting reactant?

## 38.3 g

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Chemical reactions and Stoichiometry

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find limiting reactant. First, we need to divide each of the reactive masses by the respective, more massive. In the case of the platinum compound that's 415 09 Gramps and everyone will, which is equal to 0.13 for moles. This compound. We're gonna do the same for the ammonia find. How many moles is that we have the people, too. It's more massive people to 17.3 grams, and everyone will we find that this is equal to 2.9 More. Remember that these exists in 1 to 2 more ratios. So for everyone, more platinum compound any two moles, twice as many moles. Pneumonia. Clearly two moles is much, much bigger. Then twice this number of moles. We can do the math that many moles of the platinum compound rule. You're a point to 68 moles of ammonia. We have way more ammonia that that, and that's how we determine that the platinum compound is the limiting reactions, and thus we use that to determine how much product is produced. So because the limiting reactant, the limiting reactant has a 1 to 1 more ratio with the product. Then if I started with 0.134 moles of this platinum compound, we're gonna make zero point. When they used black on this, we're gonna make 0.134 moles, uh, platinum product. Then we can move on and find how many grams that corresponds to to find Gramps. We're going to multiply by the molar mass, which is 300.5 grams of this platinum compound. For every one mole of the same, That means that are more units cancel. And we find that we have 40.3 grams. This is flattened, but we already know that not all of that suspect miss collectively 95% collected. So what we're gonna do is we're going to multiply by that fraction 0.95 The same thing is 95 out of 100. When we do that, we get instead of 40.3 grams, we get 38.3 gram of plotting, and that is our actual yield. So this 40.3 was theoretical yields. We multiply the theoretical yield by the percent yield to find what fraction is actually collected. This this is the actual

Rice University

#### Topics

Chemical reactions and Stoichiometry

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