Stoichiometry lab problem

Question

Stoichiometry Lab Problem

Assume you are given these materials:

beaker

Electronic scale

Sodium hydrogen carbonate

2M HCl

Specify size of equipment used: E.g. 500 ml beaker was used.

design a method to determine the mass of CO2 produced in the reaction. This is done by comparing the mass of reactants to mass of products.

You are limited in using no more than 2.000 g sodium hydrogen carbonate and 100.0 ml 2.00 M HCl (2.00 M is equivalent to 73.0 g/L)

Chemical equation: Na2CO3 + 2HCl ——> 2NaCl + CO2 + H20

Calculations:

Need to show calculations for the following:

Molar mass of each reactant and product

Determination of limiting reagent

Theoretical Yield of carbon dioxide

Experimental Yield of carbon dioxide

% Yield of carbon dioxide

% Error

Answer 1

Hi Ashton,

This is an experiment commonly performed in undergraduate general chemistry labs and can be used to demonstrate the law of conservation of mass, which states that "matter is neither created or destroyed" in a chemical reaction. Therefore, the mass of your reactants must equal the mass of your products after your reaction has reached equilibrium or has been fully converted from reactants to products.

The reagents mentioned in your post will take part in an acid-base neutralization reaction, producing heat, gas, water, and aqueous sodium chloride according to the following chemical reaction:

NaHCO_3(aq) + HCl_(aq) → CO_2(g) + H₂O_(l) + NaCl_(aq)

Because the carbon dioxide gas will be lost from the reaction vessel upon formation of the products, the remaining reactants will be only water with dissolved sodium chloride. Taking advantage of the physical properties of water and NaCl, we can boil the solution to drive off the water, leaving only solid NaCl. This is possible because water boils at 100 ^οC and NaCl is very thermally stable (with a melting point ~800 ^οC). With this knowledge, we can construct a reasonable method to determine the mass of carbon dioxide produced in this reaction.

Obtain a 100 mL beaker and obtain its clean dry mass. Add ~ 0.5 g of sodium bicarbonate to the beaker and record the mass of the beaker filled with sodium bicarbonate to determine to precise mass of sodium bicarbonate. Using the molecular weight of sodium bicarbonate, determine the theoretical yield of carbon dioxide using the molar conversion ratio provided in the chemical reaction (Hint - it's 1:1). Afterward, because NaHCO₃ and HCl reaction in a 1:1 molar ratio, we can use the molecular weight of HCl to determine the volume of hydrochloric acid needed to completely react with the sodium bicarbonate. Afterwards, convert this numerical value from liters to milliiters, rounding up to the nearest increment so that HCl is added in excess (making NaHCO₃ the limiting reagent).

After adding the HCl to the beaker containing NaHCO₃, the solution will begin to fizz as CO₂ gas evolves from the reaction medium. Once the solution stops producing gas, the beaker (now containing only NaHCO₃ and water) will be placed onto a hot plate to boil off the water. Once the water has been completely evaporated, allow the beaker to cool and obtain a final mass of your NaCl product. Now, using the experimentally determined mass of NaCl and the formula weight, determine the moles of NaCl produced and, using your 1:1 molar ratio conversion, find the moles of CO₂ produced and convert to mass using carbon dioxide's molecular weight. Finally divide the experimentally determined yield (actual yield) of carbon dioxide by the theoretical yield and multiply by 100 to find your percent yield.

I hope this explanation helps! Please let me know if you have any more questions.

Jake