Chemistry Assignment
Exercise # 3: [5 Marks]Given the following data
Calculate ΔH0 for the reaction using the Hess law.
Exercise # 3: [4 Marks]
In an experiment 26.0 g of powdered iron (III) oxide is mixed with 3g carbon and heated to 500°C in a
rigid 6.0 L reactor. The following reaction occurred:
Assume that the reaction is 100% complete, the volume of Fe(s) and C(s) is small enough to be
ignored, and the temperature of the reactor is maintained at 500 °C.
1. Write the balanced reaction.
2. Calculate the number of moles of gas formed.
3. What will be the pressure of the gas in the reactor after the reaction?
Exercise # 3: [5 Marks]
A chemist has to titrate an acid with a molecular formula containing only carbon, hydrogen, and oxygen
with the respective percentages: 53.66% (C), 4.09% (H) and 42.25% (O) by mass.
To reach the equivalence point the chemist used 18.02 mL of NaOH solution 0.0406 (M) to
neutralize 0.3602 g of this acid.
Assuming that the acid is monoprotic (there is only one acidic hydrogen per molecule of acid):
1. Calculate the number of mole of acid used in the titration.
2. What is the empirical formula of the acid?
3. What is the molecular formula of the acid?
Exercise # 4: [6 Marks]
Answer to the following short questions:
1. What is the percentage of chlorine present in MgCl2?
2. What is the volume in (L) of 25000 mg of oil if its density is 881 Kg/m3?
3. Find the error(s) and rewrite the text in the correct form.
“According to the Dalton model for the atomic structure, the atomic structure is
composed of a nucleus in the center and electrons orbiting around it. The Nucleus has
always the same number of protons and neutrons and they are located in the Nucleus.
The nucleus carries almost the whole of the mass of the atom. The nucleus is positively
charged and the electron is negatively charged. Anions are obtained when electrons
are lost. Anions and Cations form salts via ionic bonding. Salts are always soluble in
water. All Covalent compounds (molecules) are not soluble in water”.
4. What is the oxidation number of the Sulphur atom in HSO4-.
5. The following equation describes the burning of hexane (C6H14) in oxygen:
2 C6H14 + 19 O2
12 CO2 + 14 H2O
How many mole of water would be produced if 0.4 mole of hexane was burnt in excess
oxygen?
