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3 years ago

In both physical and chemical changes,

Chemistry

1 answer:

Ivanshal [37]3 years ago

4 0

Answer:

option a. energy can be gained or lost.

Explanation:

Energy can be gained or lost in both physical and chemical changes.

Most physical changes involve energy gain or loss. For example:

Melting: for a substance to change from solid to liquid, the substance has to gain energy to increase the kinetic energy of the particles and they can overcome the forces of attraction and separate.

Similar reasoning can be made about freezing, evaporation, condensation, and many other physical changes.

As per chemical changes, in order to the reactant substances break their bonds energy must be gained, and as new bonds are formed to constitute the product substaces energy is loss. The net change of energy will tell if the reaction is endothermic (net gain of energy) or exothermic (net release or loss of energy).

In order to meet the energy conservation law, the energy that is gained or lost by a substance is lost or gained by other substance.

As per the options b. and c. the law of conservation of mass states that energy can be never be created or destroyed, so those options are incorrect.

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An enclosed vessel contains 2.5g of 9b nitrogen and 13.3g of chlorine at s.T.P. Of What will be the partial pressure of the Il n

kow [346]

Answer:

0.535 atm

Explanation:

Since the volume of the tank is constant, we use Gay- Lussac's law to find the pressure at 180°C.

So, P₁/T₁ = P₂/T₂ where P₁ = pressure at S.T.P = 1 atm, T₁ = temperature at S.T.P = 273.15 K, P₂ = pressure of gas at 180 °C and T₂ = 180 °C = 273.15 + 180 K = 453.15 K

So, P₁/T₁ = P₂/T₂

P₂ = P₁T₂/T₁

Substituting the values of the variables into the equation, we have

P₂ = P₁T₂/T₁

P₂ = 1 atm × 453.15 K/273.15 K

P₂ = 1 atm × 1.66

P₂ = 1.66 atm

We now need to find the total number of moles of each gas present

number of moles of nitrogen = mass of nitrogen, m/molar mass of nitrogen molecule M

n = m/M

m = 2.5 g and M = 2 × atomic mass of nitrogen (since it is diatomic) = 2 × 14 g/mol = 28 g/mol

So, n = 2.5 g/28 g/mol

n = 0.089 mol

number of moles of chlorine, n' = mass of chlorine, m'/molar mass of chlorine molecule M'

n' = m'/M'

m' = 13.3 g and M = 2 × atomic mass of chlorine (since it is diatomic) = 2 × 35.5 g/mol = 71 g/mol

So, n' = 13.3 g/71 g/mol

n' = 0.187 mol

So, the total number of moles of gas present is n" = n + n' = 0.089 mol + 0.187 mol = 0.276 mol

So, the partial pressure due to nitrogen gas, P = mole fraction of nitrogen × pressure of gas at 180 °C

P = n/n" × P₂

P = 0.089 mol/0.276 mol × 1.66 atm

P = 0.322 × 1.66 atm

P = 0.535 atm

8 0

3 years ago

The kilocalories in one can of cola if it has 40. g of carbohydrate and no fat or protein

Marysya12 [62]

Answer:

One can of cola contain 0.16 kcal of carbohydrates.

Explanation:

Given data:

mass of cola can = 40 g

kilocalories of carbohydrates = ?

Solution:

we know that there are 4 cal of carbohydrates per gram.

40 g × 4 cal/g = 160 cal

Now we will convert calories into kilocalories. There are 1000 calories in one kilocalories so,

160/1000 = 0.16 kcal

so, one can of cola contain 0.16 kcal of carbohydrates.

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3 years ago

What is pH - discuss the pH scale

Dmitry_Shevchenko [17]

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3 years ago

as the bright sun shines upon the water the water slowly disappears the same sunlight gives energy to the surrounding plants to

8090 [49]

Well when the sun makes water dissaper thats usually evaporation.

The chemical changes is when the plants absorb the energy from the sunlight and convert water and carbon dioxide into sugar and oxygen gas. Physically nothing has changed. The plant still looks the sam changes occur internally these internal changes are chemical in nature.

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3 years ago

Which is true about models in science

levacccp [35]

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4 years ago