Identify the limiting reagent, and determine how many moles of the excess reagent
remain?

Question

15.0 g of zinc react with 20.0 g of iodine according to the following
equation:
2 K(s) + I2(g) -> 2 KI(s)
Identify the limiting reagent, and determine how many moles of the excess reagent
remain.

Henry Antrim · Accepted Answer

Here's what I got.

This is the balanced chemical equation that explains this synthesis reaction. #color(red)(2)"K"_ ((s)) + "I"_ (2(g)) -> 2"KI"_ ((s))# The two reactants react in a #color(red)(2):1# mole ratio, so right from the start you know that the reaction consumes twice as many moles of potassium metal than moles of iodine gas. Utilizing the molar masses of the two reactants, convert the grams you were given to moles. #15.0 color(red)(cancel(color(black)("g"))) * "1 mole K"/(39.1color(red)(cancel(color(black)("g")))) = "0.3836 moles K"# #20.0 color(red)(cancel(color(black)("g"))) * "1 mole I"_2/(253.8color(red)(cancel(color(black)("g")))) = "0.07880 moles I"_2# You will see that you have approximately fewer moles of iodine gas than what is required in order for every mole of potassium to be involved in the reaction. This is the case because #0.07880# moles of iodine gas will only allow for #0.07880color(red)(cancel(color(black)("moles I"2))) * (color(red)(2)color(white)(a)"moles K")/(1color(red)(cancel(color(black)("mole I"2)))) = "0.1576 moles K"# to participate in the reaction; consequently, iodine gas will be the limiting reagent, which naturally suggests an excess of potassium. The quantity of potassium that does not react will be equivalent to #n_"K remaining" = "0.3836 moles" - "0.1576 moles"# #n_"K remaining" = color(green)(|bar(ul(color(white)(a/a)"0.226 moles K"color(white)(a/a)|)))# Three sig figs are used to round the result.

Avery Adams · Answer

undefined To identify the limiting reagent in a chemical reaction, you need to compare the moles of each reactant to the stoichiometric ratio given by the balanced chemical equation. The reactant that produces the least amount of product is the limiting reagent. Once you identify the limiting reagent, you can use the amount of that reagent consumed to calculate how much of the excess reagent remains.

Identify the limiting reagent, and determine how many moles of the excess reagent remain?

15.0 g of zinc react with 20.0 g of iodine according to the following equation: 2 K(s) + I2(g) -> 2 KI(s) Identify the limiting reagent, and determine how many moles of the excess reagent remain.

15.0 g of zinc react with 20.0 g of iodine according to the following
equation:
2 K(s) + I2(g) -> 2 KI(s)
Identify the limiting reagent, and determine how many moles of the excess reagent
remain.