Chemistry Solutions and Mole Concept

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Questions and Answers

What term describes a solution that has a large amount of solute?

Homogeneous Solution

Dilute Solution

Solid Solution

Concentrated Solution (correct)

What is the correct definition of solute?

Any substance in a solid state

The substance that dissolves another (correct)

The liquid component of a solution

A type of concentrated solution

Which of the following substances can act as a solvent?

NaOH

Salt

Sugar

Ethanol (correct)

Molarity (M) is expressed as which of the following?

The number of moles of solute per liter of solution Signup and view all the answers

Which formula correctly represents Normality (N)?

N = No. of equivalents / Volume (L) Signup and view all the answers

What does the term molecular weight refer to?

The sum of the atomic weights of all atoms in a molecule Signup and view all the answers

What is the significance of the mole in chemistry?

It standardizes the amount of substance in terms of particles Signup and view all the answers

What is the characteristic of a homogeneous mixture?

It has a uniform composition throughout Signup and view all the answers

What is the equivalent weight of H2SO4 if its molecular weight is 98 g/mol?

49 g/equiv Signup and view all the answers

Which formula correctly represents the relationship between ppm and molarity (M)?

ppm = M x M.wt x 1000 Signup and view all the answers

In a dilution process, if the initial concentration (N1) is 2 N and the final volume (V2) is 200 mL, what is the initial volume (V1) if the final concentration (N2) is 1 N?

100 mL Signup and view all the answers

What is the equivalent weight of NaOH?

40 g/equiv Signup and view all the answers

What is the correct expression for calculating the equivalent weight of a salt such as CaCl2?

Equivalent weight = M.Wt CaCl2 / 2 Signup and view all the answers

How is specific gravity defined?

Ratio of the density of a solution to the density of an equal volume of water Signup and view all the answers

Given that the molecular weight of H3PO4 is 98 g/mol, what is its equivalent weight?

32.67 g/equiv Signup and view all the answers

If the volume of a solution is 500 mL and the weight of the solute is 0.5 g, what is the concentration in ppm?

1000 ppm Signup and view all the answers

What is the equivalent weight of sodium carbonate (Na2CO3)?

53 gm/eq Signup and view all the answers

How much weight of sodium chloride (NaCl) is needed to prepare a solution of 58000 PPM in 200 ml of water?

11.6 g Signup and view all the answers

What is the molarity of a 58000 PPM sodium chloride solution?

1 M Signup and view all the answers

How can you determine the volume of a solution needed for a given concentration in PPM?

Use the formula V(L) = weight(mg) / PPM Signup and view all the answers

What is the equivalent weight of sodium chloride (NaCl)?

58 gm/eq Signup and view all the answers

In preparing a 2000 PPM solution of CaCl2 from 5 mg, how much volume is obtained?

2.5 mL Signup and view all the answers

What is the molecular weight of ammonia (NH3)?

17 gm/mol Signup and view all the answers

What weight of sodium bicarbonate is needed to prepare 0.25 L of a 1.6 N solution?

14 gm Signup and view all the answers

What is the molarity of concentrated hydrochloric acid with 38% concentration and specific gravity of 1.19?

12.5 M Signup and view all the answers

Which of the following is the correct formula used to determine the volume required when diluting a solution?

M1 x V1 = M2 x V2 Signup and view all the answers

How many milliliters of concentrated sulfuric acid (94% concentration, density 1.831 g/cm³) are needed to prepare 1 liter of a 0.1 M solution?

5.7 mL Signup and view all the answers

What is the normality of a 13% sulfuric acid solution with a specific gravity of 1.090?

2.8 N Signup and view all the answers

If you want to prepare 500 mL of a 0.1 N K2Cr2O7 solution from a 0.250 N solution, what is the required volume of the concentrated solution?

200 mL Signup and view all the answers

What is the molarity of a solution containing 10 gm of H2SO4 in 250 ml?

0.4 M Signup and view all the answers

What is the molarity of a concentrated sulfuric acid solution if its density is 1.831 g/cm³ and it is 94% concentrated?

17.5 M Signup and view all the answers

What is the normality of the NaOH solution containing 6 gm in 500 ml?

0.3 N Signup and view all the answers

When preparing a solution, if the required concentration is 0.2 M for a volume of 0.5 L, what is the equation used to find the volume of the concentrated hydrochloric acid needed?

V1 = (0.2 x 500) / 12.5 Signup and view all the answers

What is the molarity of a solution with 25 gm of AgNO3 in 1L of solution?

0.14 M Signup and view all the answers

The molar weight of sulfuric acid (H2SO4) is calculated as which of the following?

98 g/mol Signup and view all the answers

What is the normality of the AgNO3 solution if the molarity is 0.14 M?

0.14 N Signup and view all the answers

How many grams of NaCl are needed to prepare a 0.2 N solution in 250 ml of water?

5.85 g Signup and view all the answers

What volume of concentrated sulphuric acid is needed to prepare 0.6 L of a 0.2 M solution?

67.99 ml Signup and view all the answers

What is the normality of the KCl solution prepared as 0.3 N in 500 ml?

0.3 N Signup and view all the answers

What is the final concentration in molarity of a solution if 100 mL of 0.5 N AgNO3 is diluted to make a 0.3 N solution?

0.3 M Signup and view all the answers

Study Notes

Solution Definitions

A solution is a homogeneous mixture of two or more substances; concentrations can vary within limits.
Concentrated solutions contain a high amount of solute.
Dilute solutions contain a small amount of solute.
A solute dissolves in a solvent to form a solution.

Components of a Solution

Solute: The substance that dissolves in the solution (e.g., sugar, salt, NaOH, Na₂CO₃).
Solvent: The substance that dissolves the solute to form a solution (e.g., water, acetone, ether, ethanol).
Solution: A mixture of two or more pure substances where one substance is dissolved in another homogeneously. A solution has the same concentration throughout.

Mole Concept

Mole: A fundamental unit of mass used by chemists to represent a large number of elementary particles (atoms, molecules, ions, electrons, etc.) of any substance.
Mole = weight (gram) / Molecular Weight (gram/mol)

Molecular Weight

Molecular Weight (M.wt): The sum of the atomic weights of all atoms in a molecule of a substance, measured in gram/mol.
Examples provided include CH₄, SO₃, NH₃, H₂O, (NH₄)₂CrO₄, and Ba(NO₃)₂ with their calculated molecular weights.

Molarity (M)

Molarity (M): The concentration of a solution expressed as the number of moles of solute per liter of solution.
M = Mole / Volume(L)
M = (weight × 1000) / (M.Wt × volume(ml))

Normality (N)

Normality (N): The concentration of a solution expressed as the number of gram equivalents of solute per liter of solution.
N = No. of equivalents (eq) / Volume (L)
N = (weight × 1000) / (eq. wt × volume(ml))

Equivalent Weights

Acid: eq.wt acid = M.Wt acid / No. of active H⁺. Examples include H₂SO₄, H₃PO₄, and HCl.
Base: eq.wt base = M.Wt base / No. of active OH⁻. Examples include NaOH and Ca(OH)₂.
Salts: eq.wt = M.Wt / (number of cation or anion * its charge). Examples include NaCl and CaCl₂.

Part Per Million (ppm)

ppm: Milligrams of solute per liter of solution.
ppm = wt(mg) / V(L)
ppm = wt(g) × 10⁶ / V(mL)

Relationship Between Molarity (M), Normality (N), and ppm

ppm = M × M.wt × 1000
ppm = N × Eq.wt × 1000
N = n × M (where n = number of H⁺ for acids or number of OH⁻ for bases).

Density and Specific Gravity

Density: Weight per unit volume at a specified temperature (usually g/mL or g/cm³).
Specific Gravity (sp. gr.): The ratio of the mass of a substance to the mass of an equal volume of water at a specific temperature (often 20°C or 4°C).
M = (% × density × 1000) / M.wt; and M = (% × sp. gr. × 1000) / M.wt

Dilution

Dilution: The process of adding more solvent to a solution to lower its concentration. The same amount of solute is present, but it's distributed in a larger volume of solvent.
N₁ × V₁ = N₂ × V₂
M₁ × V₁ = M₂ × V₂

Examples of Preparing Standard Solutions (calculations provided)

Examples demonstrate the calculations for preparing various standard solutions (e.g., NaOH, Na₂CO₃, NaCl, H₂SO₄, HCl, and others).

Homework Problems

Homework problems are presented requiring the calculation of molarity, normality, or volumes for solutions (e.g., specific concentration and volume needed).

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Description

Test your knowledge on the definitions and components of solutions, as well as the mole concept in chemistry. This quiz covers essential terms such as solute, solvent, and molecular weight. Perfect for those studying chemistry at any level!