Control question
Q1. Define the term solution. How many types of solutions are formed?
Write briefly about each type with an example.
Answer: Whenever two or more than two
non-reacting substances are mixed, the resulting system is called a mixture. A
solution is a homogeneous mixture of two or more substances in their molecular
level. The component having the same physical state as that of the resulting
solution is called solvent, the other being the solute. If both are of same
state, the larger amount component is solvent. Types of solution: aqueous, un-saturated, saturated, supersaturated, Liquid-gas,
liquid-liquid, solid-solid, gas-solid, solid-liquid.
Q2. Give an example Example of liquid-liquid
solution?
Answer: Rubbing alcohol is relatively a liquid-liquid solution. There's
water and some kind of liquid alcohol compound in it.
Q3. What gases are liquid at room temperature?
Answer: Many materials exist as both a gas and a liquid at room temperature
(about 200C). Examples include water, alcohol andgasoline. These
materials will evaporate until the partial pressureof the material in the local
atmosphere balances the pressure atthe boil ling point for the fluid.
Q4. How does solubility of solids and gases change with
temperature?
Answer: The solubility of solids generally gets higher as the temperature
gets higher. (apart from with calcium hydroxide- limewater). The opposite is
true for gases- their solubility decreases as the temperature
increases.
Q5. Why do gases always tend to be less soluble in liquids as the
temperature is raised?
Answer: As temperature increases the mean kinetic energy of all particles
present increase, allowing for the gases dissolved to evaporate more readily, as
they are in a greater state of vibratory motion - that is they are present in a
more gaseous form. Phase is determined by the extent of motion of particles,
which is determined by the intermolecular forces acting between molecules. An
increase in temperature will also increase the motion of dissolved particles by
weakening the forces acting between the solute and solvent. This allows the
dissolved gases to evaporate out of solution. Hence an increase in temperature
corresponds to a decrease in the solubility of gases in liquids.
Q6. State Henry’s law and mention some important
applications?
Answer: Chemistry law which states that the mass of a gas which will
dissolve into a solution is directly proportional to the partial pressure of
that gas above the solution.
Q7. What is the difference between molarity and
molality?
Answer: The difference is in the denominators. Molarity (M) - the number of
moles of solute divided by the number of liters of solution. Molality (m) - the
number of moles of solute divided by the number of kilograms of
solvent.
Q8. What is relation between molarity and molality and
normality?
Answer: "Normality" refers to
the activity of a reagent: gram equivelant dissolve in a liter?. "Molarity"
refers the numbers of moles of the solute present per litre of the solution..
"Molality" refers the numbers of moles of solute present in 1000 grams of the
solvent.. Thus, for hydrochloric acid (HCl) and sodium hydroxide (NaOH) the
normality is equal to the molarity. But for dibasic substances like sulfuric
acid (H2SO4) or barium hydroxide Ba(OH)2, the
normality is twice the molarity. For a tribasic substance, normality would be
three times the molarity and so forth. Molarity measures the number of moles of
a substance present in perliter of solution. Normality is basically a measure
ofconcentration that is in the mixture of solution.
Q9. What is a solvent and a solute?
Answer: Solute: The substance that is dissolved in a solvent is called
solute, e.g. sugar is solute, it is used in small amount. Solvent: The substance
that dissolves solute to form solution, e.g. water is solvent, it is used in
large amount.
Q10. Describe two examples of solutions in nature and explain why each is
important.
Answer:
1) The ocean - great sources of Na+, Cl+,
K+, and many trace metals, not to mention water (through evaporation
in the water cycle).
2) Petroleum - the source of hydrocarbons, which once separated gives
us everything from gas to drive our cars to fuels to power out electric plants
to raw materials for everything from the drug industry to
plastics.