Model Test Questions Chemistry Test # 8 for Chapter # 6 (Solution)
Short
Answer-questions
Q1. Write the
differences between following:
(i) diluted and concentrated solution
(ii) Saturated
and unsaturated solution
(iii) Saturated and supersaturated solution
(iv) suspension and colloid
(v) Solution and suspension
(vi) Solution and Colloid
Q2. Air is a solution of general gases
containing oxygen, carbon dioxide, nitrogen and other gases (inert gases).
Which one of the gas is called solvent and why?
Q3. Brass contains 20% zinc and 80% copper. Identify state of solute and solvent in this solution? Also write the type of solution.
Q4. A student asked to prepare 10%(m/m)
solution of sugar. How much solvent will be required to prepare this solution?
Q5. Which one of the solution is more
diluted; 2M or 3M?
Q6. Why solute dissolve in solvent?
Q7.Why benzene does not dissolve in water?
Q8.What is the main reason that solute did not dissolve in water?
Q9. Why solution called mixture?
Q10. How is solution formed?
Q11. What is aqueous solution?
Q12. Write any two examples of solute and solvent.
Q13. Suppose solute-solute forces are weaker than those of solute-solvent
forces. Will solution be formed?
Q14. Explain the general
principle for solubility, “like dissolves like”?
OR
Explain the solubility with reference to
“like dissolve like” principle.
Q15. Define solution and
explain the major components of solution?
Q16. How is a colloid different from a solution?
Q17. Which one is colloidal solution, Starch solution or Glucose solution?
Q18. Paint is colloidal solution. Give reason?
Q19. Why paints should be stir thoroughly before using?
Q20. Write two examples
of each of colloids and suspension.
Q21. Justify that milk is a colloidal solution.
Q22. Why does the colloidal show tyndall effect?
Q23. Why sugar solution
scatters the light?
Q24. Polar and ionic solutes
dissolve in polar solvent only. Why?
Q25. Why does Polar
solute not dissolve in nonpolar solvent?
Q26. How are solutions
beneficial for community ? OR Why solutions are important for us?
Q27. Why salt dissolves
in water?
Q28. Why gasoline does not
dissolve in water?
Q29. Define
concentration, false solution, Dilution, Solubility, Molarity, mass/volume
percent
Q30. Write the example of each type of solution.
Long
Answer-questions
Q1. What is the
difference between solution, colloids and suspension?
Q2. Explain the solute-solvent interaction to prepare sodium chloride
solution.
OR
Explain the attraction of Na and Cl ions
for water molecule.
Q3.Describe how to
prepare dilute solution from concentrated solution.
Q4. Define the term
solubility. How does nature of solute and solvent determine the extent of
dissolution? Why the solubility of a salt increases with the increase in
temperature?
Numericals
Percent Concentration
Q1. Determine the percentage concentration of the solution obtained by
dissolving 10g sugar in 140g water
Q2. Calculate the percentage concentration (m/m) of the solution obtained by
dissolving 15g salt in 110g water.
(Answer; 12% by mass)
Q3. Calculate the volume/volume percent of solution obtained by mixing 25 cm3
of ethanol in water to produce 150 cm3 of the solution.( Answer;
16.7% by volume)
Q4.A solution of 20 cm3 of alcohol is dissolved in 80cm3
of water. Calculate the concentration (v/v) of this solution.
Q5. What volume of 0.5M acid is needed to neutralize 200 ml of 4M base?
Q6. How much sodium hydroxide (NaOH) is required to prepare 400 cm3
of 0.3M solution?
Q7. A solution contains 43.5 g of water and
6.5 g of NaCl. Determine its percentage by mass.
Dilution
Q1. 10M HNO3 solution is available in laboratory. How would you
prepare 500 cm3 of 0.1M solution?
Q1. How would you prepare 500 cm3 of 0.20 M NaOH (aq) from a stock
solution of 1.5 M NaOH? (Answer; 66.67 cm3)
Q2. How do you prepare 100 ml of 0.40 M MgSO4 from a stock
solution of 2.0M MgSO4? (Answer; 20 cm3)
Q4.A sample of sulphuric acid has the molarity 20M. How many cm3
of solution should you use to prepare 500 cm3 of 0.5M H2SO4
? ( Answer; 12.5cm3)
Molarity
Q1. 20 gram of salt is dissolved in 500 cm3 of a solution.
Calculate the molarity of that solution. (Answer; 0.683
mole/dm3)
Q2. What is the molarity of the solution prepared by dissolving 1.25 g of HCl
gas into enough water to make 30 cm3 of solution?
Q3. A solution of potassium chloride was prepared by dissolving 2.5 g of
potassium chloride (KCl) in water and making the volume up to 100 cm3.
Find the concentration of solution in mol/ dm3.
Q4. A mineral water bottle contains 28 mg of calcium in 100 cm3 of
solution. What is the concentration in g/dm3?
Q5. 53 g of Na2CO3 is
dissolved in water to make its 750 ml.
Calculate its molarity.
Q6. 5.3 g of Na2CO3 was
dissolved in 800 g water, calculate its molality of solution.
Mass from Molarity
Q1. What is the mass of oxalic acid (H2C2O4)
present in 100 cm3 of 2 molar solution? (Answer; 8 g)
Q2. A flask contains 0.25 M NaOH solution. What mass of NaOH is present per
dm3 of solution?
Q3. A solution of NaOH has concentration 1.2M, calculate the mass of NaOH in
g/dm3 in this solution.
Q4. What mass of Na2CO3
is required to prepare its 250 cm3 solution of 0.5 M?
Q5. What mass of K2CO3
is dissolved in 1200 g water to prepare its half molal solution?
Q6. How many dm3 of 0.25 M NaOH
solution must be measured to dissolve 0.1 mole of NaOH?
Answers of Short
Answer-questions
Q1. Write the differences
between following:
(i) diluted and concentrated solution.
(ii) Saturated
and unsaturated solution
(iii) Saturated and supersaturated solution
(iv)suspension and colloid
(v) Solution and suspension
(vi) Solution and Colloid
Answer
difference between solution,
Suspension and Colloids
difference between Saturated, Unsaturated and Supersaturated solution
difference between diluted and concentrated solution
Q2. Air is a solution of general gases containing oxygen, carbon dioxide, nitrogen and other gases (inert gases). Which one of the gas is called solvent and why?
Answer
In a
solution, the larger component is the solvent and the minor component(s) is the
solute. In the air, Nitrogen is the solvent (majority component), and oxygen
(minority component) is the solute.
air is a homogeneous mixture of many
different gases and therefore qualifies as a solution. Approximately 78% of the
atmosphere is nitrogen, making it the solvent for this solution. The next major
constituent is oxygen (about 21%), followed by the inert gas argon (0.9%),
carbon dioxide (0.03%) and trace amounts of neon, methane, helium, and other
gases are solute.
Q3. Brass contains 20% zinc and 80% copper. Identify state of solute and solvent in this solution? Also write the type of solution.
Answer
Brass is an alloy which is one of the type of solution called solid-solid solution. Copper being the larger component is the solvent while zinc being the smaller component is the solute.
Q4. A student asked to prepare 10% (m/m) solution of sugar. How much solvent will be required to prepare this solution?
Answer
A 10% (m/m) solution contains 10 g solute in 90 g of solvent. Hence 10%(m/m) solution of sugar contains 10 g sugar dissolved in 90 g of solvent to give 100 g of solution.
Q5. Which one of the solution is more diluted; 2M or 3M?
Answer
2M solution
contains 2 moles of solute per dm3 of solution while 3M solution
contains 3 moles of solute per dm3 of solution. A solution
containing less moles of solute is more diluted. Hence 2M solution is more
diluted than 3M solution.
Q6. Why solute dissolve in solvent?
Answer
The process of
solution formation depends upon the relative strength of attractive forces
between solute-solute, solvent-solvent and solute-solvent. A solute will
dissolve in a solvent if the solute-solvent forces of attraction are greater
enough to overcome the solute-solute and solvent-solvent forces of attraction.
Q7. Why benzene does not dissolve in water?
Answer
The general,
principle of solubility is “Like dissolves like”. polar or ionic solutes easily
dissolve in polar solvents whereas non-polar solutes easily dissolve in
non-polar solvents and hence it is said that like dissolves like. Benzene being
non-polar does not dissolve in polar solvent water.
Q8. What is the main reason that solute did not dissolve in water?
Answer
In order to dissolve the solute into
solvent, the following conditions must be fulfilled.
(i) Solute-Solute
bonding should be broken.
(ii) Solvent-Solvent
bonding should be broken to provide space for solute particles.
(iii) Solute-Solvent
attraction should be maximized.
When
solute-solute or solvent-solvent interactions are much more than solute-solvent
interaction, a solution will not form and solute does not dissolve in solvent
water.
Q9. Why solution called mixture?
Answer
A solution is
a special type of homogeneous mixture composed of two or more substances. In such a mixture,
a solute is a substance dissolved in another
substance, known as a solvent. The mixing process
of a solution happens at a scale where the effects of chemical polarity are
involved, resulting in interactions that are specific to solvation.
a mixture is a material made up of two or more different chemical substances
which are not chemically bonded. A mixture is the physical combination of two
or more substances in which the identities are retained and can be physically
separatede.g. solutions, suspensions and colloids
Q10. How is solution formed?
Answer
In order to dissolve the solute into
solvent, the following conditions must be fulfilled.
(i) Solute-Solute
bonding should be broken.
(ii) Solvent-Solvent
bonding should be broken to provide space for solute particles.
(iii) Solute-Solvent
attraction should be maximized.
When
solute-solute or solvent-solvent interactions are much more than solute-solvent
interaction, a solution will not form.
The process of solution formation depends upon the relative strength of attractive forces between solute-solute, solvent-solvent and solute-solvent. A solute will dissolve in a solvent if the solute-solvent forces of attraction are greater enough to overcome the solute-solute and solvent-solvent forces of attraction. A solute will not dissolve if the solute-solvent forces of attraction are weaker than individual solute and solvent intermolecular attractions.
Q11. What is aqueous solution?
Answer
An aqueous
solution is formed by dissolving a substance in water. The word aqueous is
derived from the Latin word called aqua meaning water. Sugar, salt, and acid in
water are the examples of aqueous solution. In aqueous solution, water (H2O)
is present in greater amount and termed as solvent.
Q12. Write any two examples of solute and solvent.
Answer
(i) in 5% aqueous sugar solution, sugar is
solute as it is in smaller amount.
(ii) in 10% aqueous table salt solution, water is solvent as it is
in larger amount.
Q29. Define concentration, false solution, Dilution, Solubility, Molarity, mass/volume percent
Answer
concentration
The concentration (strength) of a solution is the given amount (mass or
volume) of the solute present in known amount of solvent or solution. It is
also the ratio of amount of solute to the amount of solution or ratio of amount
of solute to the amount of solvent. The proportion of solute in a solution is
called concentration.
false solution
A homogenous
mixture in which solute particles are larger than those present in the true
solution but not large enough to be seen by naked eyes are called false
solution or colloidal solution.
Dilution
Dilution refers to the process of adding additional solvent to a solution
to decrease its concentration. This process keeps the amount of solute
constant, but increases the total amount of solution, thereby decreasing its
final concentration. Dilution can also be achieved by mixing a solution of
higher concentration with an identical solution of lesser concentration.
Mass by volume
percent (%m/v)
It is the mass of the solute in grams
dissolved per 100cm3 of the solution.
Molarity
Molarity is defined as the number of moles of solute dissolved per 1 dm3
(1 liter) of a solution denoted by M.
Solubility
Solubility is the maximum amount of solute in grams required to be
dissolved in 100 g or 100 ml of a solvent to prepare a saturated solution at
room temperature.
Q30. Write the example of each type of solution.
Answer
There are 9 different types of solutions according to the three states of
solute and solvent.
Q2. Explain the solute-solvent interaction to prepare sodium chloride solution.
OR
Explain the attraction of Na and Cl ions for water molecule
Answer
Solubility and Solute-Solvent Interaction
In order to dissolve the solute into
solvent, the following conditions must be fulfilled.
(i) Solute-Solute
bonding should be broken.
(ii) Solvent-Solvent
bonding should be broken to provide space for solute particles.
(iii) Solute-Solvent
attraction should be maximized.
When
solute-solute or solvent-solvent interactions are much more than solute-solvent
interaction, a solution will not form.
The process of solution formation depends upon the relative strength of attractive forces between solute-solute, solvent-solvent and solute-solvent. A solute will dissolve in a solvent if the solute-solvent forces of attraction are greater enough to overcome the solute-solute and solvent-solvent forces of attraction. A solute will not dissolve if the solute-solvent forces of attraction are weaker than individual solute and solvent intermolecular attractions.
As we know
that sodium chloride is an ionic compound. When sodium chloride (NaCl) is
placed in water, it dissolves quickly. The negative end of water molecules is
attracted to sodium ions and the positive end of water molecules is attracted
to chlorine ions. In this case, solute-solvent attractions are more in
comparison with solute-solute interaction, therefore solution of sodium
chloride is formed. These attractive forces of water are stronger enough to
overcome the attraction between Na+ and Cl‒ ions in NaCl.
The following figure shows the attraction of Na+ and Cl‒
ions with water molecules.
Q3. Describe how to prepare dilute solution from concentrated solution.
Answer
Dilute
solution contains a relatively small amount of a solute in a large amount of
solvent like adding more water to a solution. Whereas, concentrated solution
contains a relatively large amount of solute in a small amount of solvent.
Dilution of a
solution is necessary process in the laboratory, as stock solution (more concentrated)
are often purchased and stored in laboratory when the desired concentration of
solution is required can be prepared by diluting the stock solution by given
formula.
Preparing dilute solution
In a laboratory, we can make a dilute
solution from a concentrated solution by using formulas:
Where,
M1 = Molarity of concentrated
solution
V1 = Volume of Concentrated
solution
M2 = Molarity of dilute
solution
V2 = Volume of dilute solution
Q4. Define the term solubility. How does nature of solute and solvent determine the extent of dissolution? Why the solubility of a salt increases with the increase in temperature?
Answer
Definition
It is the amount of solute in grams required to be dissolved in 100 g or
100 ml of a solvent to prepare a saturated solution at room temperature.
Unit
1.The solubility is
expressed in g/100 g water or g/100 ml water at a specified temperature.
2. The practical and S.I.
unit of solubility is mole/liter (mole/dm3).
Factors Affecting Solubility
Solubility depends upon following factors:
1. Nature of solute and solvent
2. Temperature
3. Pressure
1. Effect
of Nature of Solute and Solvent/General Principles of Solubility
The general,
principle of solubility is “Like dissolves like”. Its mean that two substances
with similar intermolecular forces are likely to be soluble in one another. polar or ionic solutes easily dissolve
in polar solvents whereas non-polar solutes easily dissolve in non-polar
solvents and hence it is said that like
dissolves like.
Example
(i) Na2CO3, sugar
and alcohol are polar and dissolve in water because water is also polar. (common salt;
NaCl being an ionic compound dissolves more readily in polar solvent like water
but it is insoluble in non-polar solvents like benzene or petrol).
(ii) oil and paints being non-polar dissolve
in non-polar solvent ether. Similarly, waxes and fats dissolve in benzene and
not in water.
2. Effect
of Temperature
Solubility is directly proportional to the temperature in solid &
liquid. The solubility of solids in liquids usually increases with the rise in
temperature because hot water molecules have greater kinetic energy and collide
with solid solute more vigorously.
For example;
a greater amount of sugar will dissolve in warm water than in cold water.
(solubility of sugar in water at
0°C is 179 g/100 ml of water whereas 100°C it is 487 g/100 ml of water).
The solubility
of potassium chloride is 34.7g/cm3 at 20°C. It will become 56.7g/cm3
at 100°C.
For all gases, the solubility decreases
as the temperature of the solution increases. (The solubility of gases in a
liquid (unlike solids) decreases with increasing temperature. For this reason
when a glass of cold tape water is warmed, the bubbles of dissolved air are
seen on the inside of the glass).
No comments:
Post a Comment