Chemistry Study Material

This study material provides information on indicators, titration, mole ratios, oxidation states, acid-base reactions, pH calculations, and more in the field of chemistry.

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1. An indicator defines any substances that changes in color in response to chemical change. An
indicator solution drop is added to titration at the start to allow determination of the end point of
a reaction since at the reaction end point the indicator will change the color to a different color.
There is a change in color at the endpoint of a reaction since any unreacted molecules in excess
of the needed ones to attain the endpoint would undergo a reaction with the molecules of the
indicator. This results in a change in the structure of the molecules of the indicator thereby
having a change in the color.
2. The unknown solution goes to the burette. The solution will then be titrated against the titrant
that would aid in calculations that will be used in its identification.
3. Mole if acid: base in the reaction=2:3
Ca (OH) 2 is the base while H3PO4 is the acid
4. Strong base-weak acid. A reaction between a strong base and a weak acid results in excess
OH- ions in the solution that render the pH of the solution to be alkaline hence more than 7
5. Equation for reaction
HCl+ NaOH NaCl + H2O
Moles of HCl used=0.015*18.7/1000=0.0002805 moles
Mole ratio of HCl: NaOH=1:1
Moles of NaOH used=0.0002805 moles
Molarity of NaOH=0.0002805/15*1000
=0.0187 M

6. Fe is undergoing oxidation in the reaction. In the reaction, displaces V2O3 from its oxide
leading to the formation of Fe2O3 and VO. The number of oxygen atoms in VO is reduced from 3
to 1 while the number of oxygen atoms in Fe is increased from 0 to 3
7. 0. The oxidation state of any element at the elemental state is 0 since it neither loses nor gains
electrons in the state
9. The oxidizing element in the reaction is N2. The oxidation number of N2 in the reaction
reduces from 0 to -2 meaning there is donation of protons to the other reactant in the reactant
which is Mg that has been oxidised and the oxidation number increasing from 0 to +3.
2. a. Arrhenius
b. Lewis
c. Brønsted–Lowry
d. Brønsted–Lowry
3. Acid-H2SO4
Conjugate acid-H3O+
Base-H2O
Conjugate base-HSO4-
Question 4
a. Nitric (V) acid

b. Hydrogen bromide
c. Sodium hydroxide
d. Carbonic acid
5. PH 9. Sodium bicarbonate undergoes dissociation in water in which hydroxonium ions are
formed in the solution which makes the pH of the solution to be about 9
6. pH = - log ([H3O+])
-9.5= log ([H3O+])
([H3O+] =10-9.5M=3.01*10-10
7. pH = - log [H3O+].
pH=- (log 2.51*10-5) =4.6
8. The base in the forward reaction is NH3. A base is defined as a proton acceptor in a chemical
reaction. In the reaction, NH3 gains a proton lost by H2O leading to the formation of NH4+
9. Strong base-weak acid. In this reaction the strong acid will undergo complete dissociation
resulting in the formation of more OH ions that H+ ions as the acid will not completely
dissociate
10. They have a pH<7. A reaction between a strong acid and a weak base result in the formation
of an acid solution hence the pH would be less than 7.