Reactant Lab

Lab 4-B
Purpose
The purpose of this lab is to test these solutions and see what type of reaction occurs and see if a precipitate or gas forms between any of these reactions.

Research

1. Table A
Reactants in Aqueous Solutions
Predictions
(1) MgCl₂(aq) + 2NaOH(aq)
Mg(OH)₂(s) + 2NaCl(aq)
(2) FeCl₃(aq) + 3NaOH(aq)
Fe(OH)₃(s) + 3NaCl(aq)
(3) 2KCl(aq) + Na₂SO₄(aq)
K₂SO₄(s) + 2NaCl(aq)
(4) CaCl₂(aq) + 2AgNO₃(aq)
Ca(NO₃)₂(s) + Ag₂Cl(aq)
(5) CuSO₄(aq) + Na₃PO₄(aq)
Cu₃PO₄(aq) + Na₂SO₄(s)

2. Table B
Reactants
Predictions
(1) Na₂CO₃(s) + 2HCl(aq)
NaCl(aq) + CO₂(g) + H₂O(l)
(2) NH₄Cl(s) + NaOH(aq)
NaCl(aq) + NH₃(g) + H₂O

3. All safety rules

Hypothesis
In this experiment I estimate that the solutions that we are testing will either form a precipitate
Reactants
Predictions
Na₂CO₃(s) + 2HCl(aq)
The product of the reactants gave off a distinct smell; a gas had formed.
NH₄Cl(s) + NaOH(aq)
We observed that not only was there a distinct smell, but also a fizz reaction occurred when we added a drop of the solution into the reactant plate.

Source of Error
There was no true way of measuring the proper amount of how much of a substance should be mixed with the other, which could have led to false observations

Discussion
1. My predictions in the Pre lab were similar in some ways, but also differed in others. For example, most of predictions were correct about whether a reaction would take place in each solution or not, but for Reactants 2 and 3 in Table A my predictions were wrong and a reaction did not occur (from what I observed).
2. In order to predict whether a precipitate will form in a reaction, the solubility of the substances involved must be known. There are rules or guidelines determining solubility of substances. The product's' reaction with the lowest Solubility constant is the one that surely will precipitate in a chemical system. If something is soluble, a precipitate will form as a result of the reaction. To determine if something is soluble, use a solubility
I think my balanced chemical equations form the Pre-Lab could have maybe been better, but for the most part, they were similar to me and my partner’s observations.

4. I knew that a double displacement reaction occurred if there is the formation of a gas, formation of a precipitate, or formation of water from an acid-base neutralization.

a. When a gas has formed possibly. Although in Reactant 2 Table B produced a visible reaction with the fizzing, not all reactions can produce that visible sign, as observed by me and my partner in Reactant 3 Table B.

b. Na2S(aq) + 2HCl(aq)  H2S(g) + 2NaCl(aq)
In this example we see that the dihydrogen sulfide is the gas the forms out of this reaction

HNO3(aq) + KOH(aq)  KNO3(aq) + H2O(l)
In this example the acid and base react to form a salt and water

5.
a. 2K2Cr2O7(aq) + 3AlBr3(aq)  1KBr(aq) + 6Al2(Cr2O7)3(s)

b. I know that a precipitate forms because of the 1 aqueous solution as part of the product, and because aluminum is in group 5 in the solubility table, which makes it more plausible that is higher up above group, I can assume that dichromate is