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2 years ago

Classify each of the following changes as Physical or Chemical:

Chemistry

1 answer:

ddd [48]2 years ago

6 0

Explanation:

Physical changes are the changes that does not lead to any change in chemical composition of a substance.

For example, mass, density, volume are all physical changes.

On the other hand, a change that leads to formation of a new compound by changing the chemical composition of reactants or combining atoms is known as a chemical change.

For example, combustion, toxicity, reactivity etc are all chemical changes.

Therefore, given changes are identified as follows.

Coal burning : It is a combustion reaction. Hence, it is a chemical change.

Ice melting : Physical state of water changes from solid to liquid. Hence, it is a physical change.

mixing chocolate syrup with milk : No new compound is forming as there is no chemical reaction occurring. Hence, it is also a physical change.

explosion of a firecracker : It shows reactivity of fire cracker. Hence, it is a chemical reaction.

magnetizing of a screwdriver : It shows physical attraction between the magnet and screwdriver. Hence, it is a physical change.

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Calculate the molarity of a salt solution with a volume of 0.250L that contains 0.70 mol of NaCl. (SHOW WORK)

Kazeer [188]

Answer:

= 0.28M

Explanation:

data:

volume = 0.250 L

= 0.250dm^3 ( 1litre = 1dm^3)

moles = 0.70 moles

Solution:

molarity = $\frac{no. of moles}{volume in dm^3}$

= 0.70 / 0.250

molarity = 0.28 M

5 0

1 year ago

Which of the following is true concerning ψ²? A) ψ² describes the probability of finding an electron in space. B) ψ² describes t

Ilia_Sergeevich [38]

Answer:

A) ψ² describes the probability of finding an electron in space.

Explanation:

The Austrian physicist Erwin Schrödinger formulated an equation that describes the behavior and energies of submicroscopic particles in general.

The Schrödinger equation incorporates both particle behavior, in terms of mass m, and wave behavior, in terms of a wave function ψ, which depends on the location in space of the system (such as an electron in an atom).

The probability of finding the electron in a certain region in space is proportional to the square of the wave function, ψ². According to wave theory, the intensity of light is proportional to the square of the amplitude of the wave, or ψ². The most likely place to find a photon is where the intensity is greatest, that is, where the value of ψ² is greatest. A similar argument associates ψ² with the likelihood of finding an electron in regions surrounding the nucleus.

5 0

2 years ago

Air, with an initial absolute humidity of 0.016 kg water per kg dry air, is to be dehumidified for a drying process by an air co

amid [387]

Answer:

(a) The proportion of dry air bypassing the unit is 14.3%.

(b) The mass of water removed is 1.2 kg per 100 kg of dry air.

Explanation:

We can express the proportion of air that goes trough the air conditioning unit as $p_{d}$ and the proportion of air that is by-passed as $p_{bp}$ , being $p_{d}+p_{bp}=1$ .

The amount of water that goes into the drier inlet has to be 0.004 kg/kg, and can be expressed as:

$0.004 = 0.016*p_{bp}+ 0.002*p_{d}$

Replacing the first equation in the second one we have

$0.004 = 0.016*(1-p_{d})+ 0.002*p_{d}=0.016-0.016*p_{d}+0.002*p_{d}\\0.004 - 0.016 = (-0.016+0.002)*p_{d}\\-0.012 = -0.014*p_{d}\\p_{d}=\frac{-0.012}{-0.014}=0.857\\\\p_{bp}=1-p_{d}=1-0.857=0.143$

(b) Of every kg of dry air feed, 85.7% goes in to the air conditioning unit.

It takes (0.016-0.002)=0.014 kg water per kg dry air feeded.

The water removed of every 100 kg of dry air is

$100 kgDA*0.857*0.014 kgW/kgDA= 1.1998 \approx 1.2 kgW$

It can also be calculated as the difference in humiditiy between the inlet and the outlet: (0.016-0.004=0.012 kgW/kDA) and multypling by the total amount of feed (100 kgDA).

100 * 0.012 = 1.2 kgW

7 0

2 years ago

The racoon is considered a secondary conkumer because...

anastassius [24]

Answer:

Hi there!

Your answer is:

A raccoon is a secondary consumer because it most commonly eats animals! It's food eats plants, making it's food a primary consumer. A raccoon is the second animal in the chain to eat!

I hope this helps!

7 0

2 years ago

Why are things like magic, astrology and psychic predictions not considered science?

romanna [79]

Things such as magic, astrology, and psychic predictions are not considered science because there is not enough empirical and circumstantial evidence to back up the hypotheses. I hope this helps, and please mark as Brainliest answer!

3 0

2 years ago