CHEM LAB 201-003
Experiment #4 - Chemical Reactions
Pre Lab Questions:
1. Before you can write a chemical equation, what must you know?
You have to know what the products and reactants are.
2. What observations might you make that suggest that a chemical reaction has
If a gas is produced or precipitates are formed that indicates chemical reaction. Also, if color changes occur or if solids are formed.
3. How could you distinguish between NH4Cl and AgCl?
AgCl is a metal and is therefore insoluble in water. NH4Cl is water soluble.
4. Define metathesis. Give an example.
Metathesis is the exchange between atoms or groups of atoms between interacting substances. Example: NaCl (aq) + AgCl (aq) = AgCl (s) + NaNO3 (aq) aka AB +CD = AD + CB.
5. What is a precipitate?
It is a product of a reaction thats is insoluble and separates from a homogenous mixture as a solid.
6. Balance these equations:
KBrO3(s)--------> KBr(s) + O2(g)
Balanced: 2KBrO3(s)--------> 2KBr(s) + 3O2(g)
MnBr2(aq) + AgNO3(aq) --------> Mn(NO3)2(aq) + AgBr(syou
Balanced:MnAg2(aq) + 2AgNO3(aq) --------> Mn(NO3)2(aq) +2AgBr(s)
7. How could you distinguish between the gases H2 and NO2?
H2is a colorless, odorless gas while NO2 has a reddish-brown color and has a pungent toxic odor.
8. Using water, how could you distinguish between the white solids KCl and PbCl2?
You could distinguish them by their solubility. KCl is water soluble while PbCl2 is not.
9. Write equation for the decomposition of H2CO3 (aq) and H2SO3 (aq).
H2CO3(aq) -------> H2O (l) + CO2 (g)
H2SO3(aq) -------->H2O (l) + SO2 (g)
1. Complete and balance the following equations:
2HCl(aq) + Pb (NO3)2 (aq) ------> PbCl2(s) + 2HNO3(aq)
2HI(aq) + K2SO3(s) ------> 2Kl (aq) + SO2 (g) + H20 (l)
Pb(NO3)2(aq) + 2KCl(aq) ------->PbCL2(s) + 2KNO3(aq)
Ba(NO3)2 (aq) +Na2SO4(aq) --------> BaSO4(s) + 2NaNO3(aq)
K2CO3(aq) +Ba(NO3)2(aq) --------> BaCO3(s)+2KNO3 (aq)
HCl(aq) + AgNO3(aq)---------->AgCl(s) + HNO3(aq)
2. How could you separate gold from a mixture of zinc and gold?
Zinc can be dissolved in hydrogen chloride, gold is insoluble in HCl.
3. Using a hydrochloric acid solution, how could you determine whether a white powder was zinc sulfide or silver nitrate? Write balanced equations.
Silver nitrate reacts with HCl to form a white precipitate with no gas present, however zinc sulfide forms the rotten egg smelling gas H2S.
ZnS(s) + 2HCl (aq) ------> ZnCl2 (aq) + H2S (g)
AgNO3 (s) + HCl (aq) -------> AgCl (s) + HNO3 (aq)