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3 years ago

Which of the following is an example of a chemical change? alcohol evaporating (b) water boiling

Chemistry

2 answers:

Elodia [21]3 years ago

5 0

Answer: Option (c) is the correct answer.

Explanation:

A property that does not bring any change in chemical composition of a substance are known as physical properties.

For example, shape, size, mass, volume, density, etc of a substance are all physical properties.

Water boiling, iodine vaporizing , and ice melting are all physical changes.

And, a property that changes chemical composition of a substance is known as chemical property.

For example, precipitation, reactivity, toxicity etc are chemical property.

Therefore, skin burning in the Sun is a chemical property.

Thus, we can conclude that skin burning in the Sun is an example of a chemical change.

stich3 [128]3 years ago

3 0

Alcohol evaporating, water boiling, iodine evaporating and ice melting are all examples of physical changes of state.

skin burning in the sun is a chemical change as the actual skin is chemically altered by the sun

hope that helps

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A mixture of gases at a total pressure of 95 kPa contains N₂, CO₂, and O₂. The partial pressure of the CO₂ is 24 kPa and the par

Zinaida [17]

Answer:

23 kPa = Partial pressure O₂

Explanation:

In a mixture of gases, the sum of partial pressure of each gas that contains the mixture = Total pressure

Total pressure = Partial pressure N₂ + Partial pressure CO₂ + Partial pressure O₂

95 kPa = 48 kPa + 24 kPa + Partial pressure O₂

95 kPa - 48 kPa - 24 kPa = Partial pressure O₂

23 kPa = Partial pressure O₂

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3 years ago

A 0.590 gram sample of a metal, M, reacts completely with sulfuric acid according to:M(s) +H2SO4(aq) --> MSO4(aq) +H2(g)A vol

photoshop1234 [79]

Answer:

MM = 58.41 g

Explanation:

First, the data we have is according to the hydrogen which is exerting pressure. To solve this, we need to use the ideal gas equation:

PV = nRT (1)

the molar mass of any compound is calculated like this:

MM = m/n (2)

So, from (1) we solve for the moles (n) and then, this value is replace in (2).

However, before we do all that, we need to gather all the correct data.

All the species in the reaction are solid or aqueous state, with the exception of hydrogen, which is gaseous. Hydrogen is collected over water, therefore, is exerting some pressure too. The problem is not indicating if the acid or any other species is exerting pressure, so we will assume that only hydrogen and water are exerting pressure.

The total pressure exerted by the system would be:

P = Pw + PH2 (3)

We already know the total pressure which is 756 torr.

This experiment is taking place at 25 °C (298.15 K), and at this temperature, we have a reported value for water pressure which is 23.8 Torr.

Let's solve for PH2:

PH2 = P - Pw

PH2 = 756 - 23 = 733 Torr

Now, with this value, and the volume and temperature, we can calculate the moles of H2:

n = PV/RT

But first, let's convert the pressure to atm:

PH2 = 733 Torr / 760 torr * 1 atm = 0.9644 atm

now, solving for n:

n = 0.9644 * (0.255) / 0.082 * 298.15

n = 0.0101 moles

Now that we have the moles, we know that the metal and the hydrogen has a mole ratio of 1:1 according to the reaction, so, this means that:

moles M = moles H2 = 0.0101 moles

We have the moles of the metal and the mass, we can calculate the molar mass using expression (2):

MM = 0.590/0.0101

MM = 58.41 g/mol

This is the molar mass of the metal

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3 years ago

Which of the following statements is true?

sp2606 [1]

Kinetic energy on mass. gravity, and speed

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3 years ago

Which of these gives a correct trend in ionization energy

natita [175]

Answer:

C. I, III , IV

Explanation:

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.

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3 years ago

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Lilit [14]

Answer:

True

Explanation:

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