Question

Project 5: Stoichiometry

Stoichiometry is the study in which we determine the relative quantities of reactants and products in a balanced chemical equation. The law of conservation of mass states that the mass of all participants in a chemical reaction must remain constant over time. Matter is neither created nor destroyed in a chemical reaction.

1. You have 13 slices of bread and 5 slices of cheese. How many grilled cheese sandwiches can you make? What is the limiting reagent? Use the following equation where Bd = Bread and Ch = Cheese.

2 Bd + Ch   Bd2Ch

2. Some friends are coming over for an outside “fireside” dinner of cheeseburgers and s’mores.

A. Cheeseburgers:

How many cheese burgers (theoretical yield) can you make if you have 8 hamburger patties (H), 12 buns(B), 7 slices of cheese(Ch), 18 slices of tomato(T), 16 pieces of lettuce(L)and 9 slices of onion(O)? The formula for a cheeseburger is BHChT2L2O. Write a balanced equation for a cheeseburger. What is your limiting reagent?

B. S’mores:

You have one bag of marshmallows. What is the maximum number of s’mores that can be made? How many boxes of graham crackers and how many chocolate bars are needed to make this many s’mores?

a. Write a balanced chemical equation using the symbols in the table below.

Substance	Symbol	Unit Mass
Graham Cracker	Gc	7.00 g/cracker
Marshmallow	Mm	7.09 g/marshmallow
Chocolate Piece	Cp	3.30 g/piece
S’more	Gc2MmCp3	__________ g/s’more

b. Calculate the unit mass of the s’more (Gc2MmCp3).

c. If there are 454 g of marshmallows in one bag, how many marshmallows do you have?

d. The coefficients in a balanced reaction give you the ratios between all of the products and reactants. Use these ratios to relate the number of marshmallows you have to the number of graham crackers and chocolate segments needed.

i. Ratio of Mm : Gc  is ________; # of graham crackers needed is _______

ii. Ratio of Mm : Cp is _________; # of chocolate pieces needed is _________

e. Using the unit mass values, determine the total mass of graham crackers and chocolate pieces that are needed. If a box of graham crackers has a mass of 254 grams, how many boxes do you need? If one chocolate bar has a mass of 49.5 grams, how many bars do you need? (Remember that you will be purchasing whole boxes and bars.)

f. How many s’mores can be made from 100. g of each ingredient?  What is your limiting reagent?

3. When a piece of aluminum metal is dropped into hydrochloric acid, HCl, hydrogen is released as a gas and a solution of aluminum chloride forms. Write a balanced equation for this reaction. How many grams of aluminum are needed to make 5.50 grams of aluminum chloride? How many grams of hydrogen gas are given off during this reaction?

Answer 1

1.

2 Bd + Ch ----> Bd2Ch

2 breads require 1 cheese slice

13 breads requires 1/2*13 cheese slices

                  = 6.5 cheese slices

from the above Cheese slice is the limiting reagent.

2.

A)

BHChT2L2O is the formula Cheese burger

B + H + Ch + 2 T + 2 L + O -------> BHChT2L2O

among all given ingrediants only slices of cheese is 7 in number.

so the limiting reagent based on the above equation.

B)

S'mores formula is Gc2MmCp3

Gc + 2 Mm + 3 Cp ------> Gc2MmCp3

Unit mass of Gc2MmCp3 = 2*7 + 7.09 + 3*3.3 = 30.99 g

one bag contain 454g of marshmallows

number of marshmallow = 454/7 = 64.85 = 65 marshmallows