Sodium borohydride, NaBH 4 , a substance used in the synthesis of many pharmaceutical agents, can be prepared by reaction of NaH with B 2 H 6 according to the equation 2 NaH + B2H 6 → 2 NaBH 4 (b) Which reactant is limiting, and how many grams of the excess reactant will be left over?

Hi everyone today, we have a question asking us at the beginning of the reaction, there are 34.67g of copper oxide and 9.87 g of carbon monoxide. And we want to calculate the amount in grams of excess reactant that remains after the reaction has come to the completion and our reaction is copper copper oxide solid plus three carbon monoxide gashes forms to copper solid plus three carbon carbon dioxide gashes. So let's start out with our three 34 0.67 grams of copper oxide times one mole of copper oxide, divided by 175. g of copper oxide. And our grams here are canceling out, Leaving us with 0. moles of copper oxide. Next we have 9.17 g of carbon monoxide. And we're going to multiply that by one mole of carbon monoxide over .01g of carbon monoxide and our grams of carbon monoxide are going to cancel out. And that's going to leave us with 0.35- moles of carbon monoxide. And for our next step, we want to take our lowest number of moles, which is our 0.1980 and see how many moles of carbon monoxide we get. So we're going to have 0. moles of copper Times 1. 3 moles of carbon monoxide over two moles of copper Times are molar mass of carbon monoxide. So 28.01 g of carbon monoxide over one mole. So our moles of copper are canceling out, and our moles of carbon monoxide are canceling out, and that gives us 8. 1897 grams of carbon monoxide. And our last step is to take our 9.87 g -R 8. 1897, And that equals 1.55 g of carbon monoxide. So our answer here is B. Thank you for watching. Bye.

Ch.3 - Mass Relationships in Chemical Reactions

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McMurry 8th Edition

Ch.3 - Mass Relationships in Chemical Reactions

Problem 85b

Chapter 3, Problem 85b

Sodium borohydride, NaBH₄, a substance used in the synthesis of many pharmaceutical agents, can be prepared by reaction of NaH with B₂H₆ according to the equation 2 NaH + B2H₆ → 2 NaBH₄
(b) Which reactant is limiting, and how many grams of the excess reactant will be left over?

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Calculate the molar mass of NaH and B_2H_6 using the periodic table.

Determine the number of moles of each reactant using their given masses and molar masses.

Use the balanced chemical equation to find the mole ratio between NaH and B_2H_6.

Identify the limiting reactant by comparing the mole ratio of the reactants to the stoichiometric ratio from the balanced equation.

Calculate the amount of excess reactant remaining by subtracting the amount used (based on the limiting reactant) from the initial amount.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Limiting Reactant

The limiting reactant is the substance that is completely consumed first in a chemical reaction, thus determining the maximum amount of product that can be formed. To identify the limiting reactant, one must compare the mole ratios of the reactants used in the reaction with the coefficients in the balanced equation. The reactant that produces the least amount of product is the limiting reactant.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It involves using mole ratios derived from the coefficients of the balanced equation to determine how much of each reactant is needed or how much product can be formed. Understanding stoichiometry is essential for solving problems related to limiting reactants and excess reactants.

Excess Reactant

The excess reactant is the substance that remains after the reaction has gone to completion, meaning it is not completely consumed. To find the amount of excess reactant left over, one must first determine the limiting reactant and then calculate how much of the excess reactant was used based on the stoichiometric ratios. The difference between the initial amount and the amount used gives the leftover quantity.

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Textbook Question

Sodium borohydride, NaBH₄, a substance used in the synthesis of many pharmaceutical agents, can be prepared by reaction of NaH with B₂H₆ according to the equation 2 NaH + B2H₆ → 2 NaBH₄

(a) How many grams of NaBH₄ can be prepared by reaction between 8.55 g of NaH and 6.75 g of B₂H₆?

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Sodium borohydride, NaBH4, a substance used in the synthesis of many pharmaceutical agents, can be prepared by reaction of NaH with B2H6 according to the equation 2 NaH + B2H6 → 2 NaBH4 (b) Which reactant is limiting, and how many grams of the excess reactant will be left over?

Verified video answer for a similar problem:

Key Concepts

Limiting Reactant

Stoichiometry

Excess Reactant

Sodium borohydride, NaBH₄, a substance used in the synthesis of many pharmaceutical agents, can be prepared by reaction of NaH with B₂H₆ according to the equation 2 NaH + B2H₆ → 2 NaBH₄
(b) Which reactant is limiting, and how many grams of the excess reactant will be left over?