Lab 10: Mole-Mass Relationships Lab

Lab 10

Mole-Mass Relationship Labs

Shiva Senthil

7/24/17

Introduction

The purpose of this lab was to use mass-mass stoichiometry to predict the theoretical yield of a chemical reaction. The lab consisted of executing a chemical reaction with sodium bicarbonate and hydrochloric acid, which yields sodium chloride and water. After the reaction, the product was heated to isolate the salt from the water. The salt was then measured and compared to the theoretical yield.

Data

The masses of the sodium bicarbonate and the resulting product were calculated by subtracting the mass of the dish from the mass of the dish with the substance inside. 

Questions
1. Which reactant is limiting? How do you know?

The limiting reactant is the sodium bicarbonate. A certain amount (~2.00g) of sodium bicarbonate was measured for the lab. The other reactant, hydrochloric acid, was continually added until all of the sodium bicarbonate was consumed in the reaction. The hydrochloric acid was in excess, and the sodium bicarbonate limited the amount of resulting product.


2. Find the theoretical yield of NaCl based on your limiting reactant.

This is the overall balanced equation of the reaction in this lab.

A mass to mass conversion was used to find the theoretical yield of NaCl. The limiting reactant was NaHCO3, so that was used for the calculations.

There are 1.98g of sodium bicarbonate reacting with excess hydrochloric acid. To convert to moles, the 1.98g was divided by the molar mass of the substance, which is 84.007g. Since the mole ratio of NaHCO3 to NaCl is 1:1, that conversion was simply multiplying by 1/1. To convert from moles of NaCl to grams of NaCl, the number of moles was multiplied by the molar mass of NaCl, which is 58.44g. This calculation results in 1.38g of NaCl as the theoretical yield of product.

3. Find the mass for the remaining solid product after the evaporation of water based on experimental data.

This calculation is simply subtracting the mass of the evaporating dish from the combined mass of the evaporating dish and the solid product after heating.

4. Find the percent yield for this experiment for the solid product.

This calculation is dividing the experimental yield by the theoretical yield and converting to a percent. In this case, the percent yield is exactly 100%

Errors

Although the percent yield was 100%, there was mostly likely some error. The product may not have been evaporated for enough time to evaporate all of the water, and there may have been some water left. At the same time, the heat may have been too high, causing some of the product to pop and go out of the evaporating dish.

The product after heating.