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2 years ago

Explain examples of a physical and chemical change of matter

Chemistry

1 answer:

monitta2 years ago

6 0

HEY DEAR..

PHYSICAL CHANGE

Those Changes in which no new substances are formed are called physical changes. it is a temporary changes which can be reversed easily to form the original substance.

Example:- Melting of ice , Making a solution, Glowing of an electric bulb , freezing of water etc.

CHEMICAL CHANGE

Those changes in which new substances are formed are called chemical changes. it means it is permanent changes which are usually irreversible.

Example:- Burning of charcoal, fuels and cutting of trees, even digestion of food is in chemical change.

HOPE ITS HELPFULLL

BE BRAINLY.

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The answer is B

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Determine the pH of a 0.048 M hypochlorous acid (HClO) solution. Hypochlorous acid is a weak acid (Ka = 4.0 ✕ 10−8 M).

storchak [24]

pH of 0.048 M HClO is 4.35.

Explanation:

HClO is a weak acid and it is dissociated as,

HClO ⇄ H⁺ + ClO⁻

We can write the equilibrium expression as,

Ka = $$\frac{[H^{+}] [ClO^{-}] }{[HClO]}$

Ka = 4.0 × 10⁻⁸ M

4.0 × 10⁻⁸ M = $$\frac{x \times x }{0.048}$

Now we can find x by rewriting the equation as,

x² = 4.0 × 10⁻⁸ × 0.048

= 1.92 × 10⁻⁹

Taking sqrt on both sides, we will get,

x = [H⁺] = 4.38 × 10⁻⁵

pH = -log₁₀[H⁺]

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2 years ago

In the process of attempting to characterize a substance, a chemist makes the following observations: (a) The substance is a sil

Amiraneli [1.4K]

The question is incomplete, this is the complete question;

In the process of attempting to characterize a substance, a chemist makes the following observations. Which are physical properties and which are chemical properties?

(a) The substance is a silvery white, lustrous metal.

(b) The substance melts at 649 ∘C

(d) The density of the substance at 20 ∘C is 1.738 g/cm³.

(e) The substance burns in air, producing an intense white light.

(f) The substance reacts with chlorine to give a brittle white solid.

(g) The substance can be pounded into thin sheets or drawn into wires.

(h) The substance is a good conductor of electricity.

Answer:

(a) Physical

(b) Physical

(d) Physical

(e) Chemical

(f) Chemical

(g) Physical

(h) Physical

Explanation:

(a) The substance is a silvery white, lustrous metal - is appearance which is physical.

(b) The substance melts at 649 ∘C metling point is a physical measurement

(d) The density of the substance at 20 ∘C is 1.738 g/cm3 how heavy a substance is,is physical.

(e) The substance burns in air, producing an intense white light. Burning is a chemical change. It is a reaction of a substance with oxygen

(f) The substance reacts with chlorine to give a brittle white solid. This is a chemical reaction as the question says.

(g) The substance can be pounded into thin sheets or drawn into wires. Ductility is a physical change, the substance remains chemically unchanged

(h) The substance is a good conductor of electricity. Any conductivity is physical, the substance remains chemically unchanged

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