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Initial Procedures
- Separate into groups of 2 with 1 group of 3 if needed.
- Each group needs to obtain a bag labelled A and one labelled B.
- Each group get a balance and make sure it is zeroed.
- Mass each bag and put masses in following blanks.
Mass of A: __________________ g Mass of B: ______________
Background Information and more procedures
We are going to use two Substance (A and B) as our reactants. These reactants will form products (actually different groupings of A & B) by the following chemical reaction:
4 A + 3 B --> 1 A2B1 + 2 A1B2
Question: With your knowledge of the mass of each bag (do not do any counting) and how these material are going to combine (from above chemical reaction),
Which Substance A or B with run out first (write guess in here): _____________________
- Now open each bag and count how many items are in each bag and record that number here
Number of A in bag: ___________________ A Number of B in bag: _____________________B
Question: Again without calculating and from your knowledge of how many items you have of each (and chemical reaction),
Which Substance A or B will run out first (write guess here): ________________
- Now, from what you just guessed (number guess not mass guess), determine how many of the other reactant you need to completely react all of items of the substance you think will run out first (you will be use ratios or we call molar ratios in balanced chemical reaction). Please show the calculation in the following space (remember Dimensional Analysis showing work rules):
Now fill in the following information:
a. Which substance you assumed all of it reacted: ______________
b. What were the number of the other reactant needed to react all the substance in a. _____________________.
Assumed: ____________ goes to completion.
Since I have ___________ (reactant not completely used up in reaction) initially and I need ______________ numbers of _______ (reactant not completely used up) to completely react all of _________(substance that you did assume completed reacted), therefore, _________________ is the limiting reactant (one that runs out first).
Now, using the limiting reactant information (one that runs out first), determine the number of each product grouping you will get. Hint: will be using the limiting information as you starting point for stoichiometry (one calculation for each of the different product formed). Use space below for calculations.
Now, determine how much of reactant that did not get completely used up in reaction (called "in excess") by the following equation: Initial - reacted = leftover. You will need to do stoichiometry to figure out how much of that reactant used up in reaction. Again you are starting stoichiometry with limiting reactant information.
From calculations, fill in the following:
Calculated Leftover of A: ___________________
Calculated Leftover of B: ____________________
Calculated Number of A2B1: ____________
Calculated Number of A1B2: ____________
Do Experiment
Now do the reaction by putting/grouping together the reactants into the correct grouping as products. After doing this fill in the following:
a. Experimental Leftover of A : _____________
b. Experimental Leftover of B: ______________
c. Experimental Number of A2B1: ____________
d. Experimental Number of A1B2: ____________