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2 years ago

Please help!!!!

Chemistry

2 answers:

Nat2105 [25]2 years ago

8 0

Answer:

When an atom gains or loses energy, the energy of an electron can change.

An electron in an atom can move from one energy level to another when the atom gains or loses energy.

Explanation:

The possible energies that electrons in an atom

can have are called energy levels.

• An electron cannot exist between energy levels.

https://1.cdn.edl.io/tTlW7xRtvD62xSe7RcZlJr7kSR7XsL93akcgJkbGJBNNcpwY.pdf

*this link can also help* brainly ist plz

Ivan2 years ago

7 0

Answer: Option (c) is the correct answer.

Explanation:

When energy is supplied to an electron then upon absorption of energy it tends to move from a lower energy level to higher energy level.

And, when this electron moves from higher energy level to lower energy level then excess of energy absorbed by it is released in the form of visible light or radiation.

This emission of energy is also responsible for imparting color to a compound.

Thus, we can conclude that when an electron loses its energy then it may drop to a lower energy level.

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In your own words, describe a pure substance. How can elements as well as compounds be considered pure substances.

Marizza181 [45]

Answer:

Pure compounds include elements and compounds where a combination of two or more pure substances is a mixture. Only one type of atom comes in the form of a pure element. Multiple atoms consist of a molecule and different atoms consist of a compound. These are all pure substances and individually.

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2 years ago

How is the pH of an acidic substance raised?

BabaBlast [244]

Answer: 4) Concentrate it

Explanation:

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2 years ago

In an area in which electricity costs 8 cents/kilowatt-hour, a 5 kW clothes dryer runs for 90 minutes to dry a load of laundry.

Orlov [11]

90 minutes is 1.5 hours.

5 kW * 1.5 hours = 7.5 kWh

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2 years ago

3. How did your hypothesis work out? What was surprising in this experiment?

MAXImum [283]

Answer:

Whats the hypothesis and the experiment?

Explanation:

I cant really help without context

3 0

2 years ago

Reaction of 0.028 g of magnesium with excess hydrochloric acid generated 31.0 mL of hydrogen gas. The gas was collected by water

MA_775_DIABLO [31]

Explanation:

(a) It is given that magnesium is reacted with hydrochloric acid and the hydrogen evolved is collected at top. This means that hydrochloric acid will be present in a solution (HCl + Water) and the solvent will be water.

Due to evaporation some amount of water will have evaporated and would be present in vapor phase. Therefore, when the reaction occurs only hydrogen will not be present in vapor phase but, will be accompanied by water vapors as well .

Hence, Dalton's law the total pressure of the system will be sum of pressure exerted by hydrogen gas and pressure exerted by water vapors .

Let us assume that the partial pressure of hydrogen gas be " $P_H_{2}$ "

And, the partial pressure of water will be nothing but the vapor pressure of water,

Vapor pressure of water = $P_{water}$

= 19.8 mm Hg

Total pressure of the system = 746 mm Hg

Total pressure = $P_H_{2} + P_{water}$

746 = $P_H_{2}$ + 19.8

or, $P_H_{2}$ = 746-19.8

= 726.2 mm Hg

Hence, partial pressure of hydrogen gas is 726.2 mm Hg.

(b) To calculate volume at STP, we will first calculate at $22^{o}C$ and 726.2 mm Hg and than convert it to STP conditions.

Therefore, to calculate volume at $22^{o}C$ and 726.2 mm Hg we will make use of ideal gas law as follows.

P = 726.2 mm Hg

= $\frac{726.2}{760}$

= 0.955 atm

T = $22^{o}C$

= 22+273.15 = 295.15 K

V = 31 ml = $31 \times 10^{-3}$ Litre

According to the ideal gas law ,

PV = nRT

where, P = pressure of the system ,

V = volume of the gas

N = number of moles

R = 0.0821 liter atm/mole K

T = Temperature

Hence, putting the given values into the above formula as follows.

$0.955 \times 31 \times 10^{-3} = N \times 0.0821 \times 295.15$

N = $1.222 \times 10^{-3}$ moles

Now, the moles of hydrogen won't change. Therefore, let us calculate volume at STP of $1.222 \times 10^{-3}$ moles of hydrogen.

Now, at STP T = 273.15 K , P = 1 atm and N = $1.222 \times 10^{-3}$ moles

$1 \times V = 1.222 \times 10^{-3} \times 0.0821 \times 273.15 K$

V = 0.027398 Litre

= $0.027398 \times 1000$ (as 1 L = 1000 ml)

= 27.398 ml

Therefore, volume of hydrogen at STP is 27.398 ml .

(c) Now, we can write the the reaction for this case as follows.

$Mg + 2HCl \rightarrow MgCl_{2} + H_{2}$

As, weight of magnesium = 0.028 grams

Molar mass of magnesium = 24.3 grams/mole

Number of moles of magnesium = $\frac{mass}{\text{molar mass}}$

= $\frac{0.028}{24.3}$

= $1.15226 \times 10^{-3}$ moles

Since, it can be seen from the reaction that

1 mole of Magnesium = 1 mole of hydrogen

and, moles of hydrogen = $1.15226 \times 10^{-3}$ moles

= 0.001523 moles

Hence, theoretical number of moles of hydrogen that can be produced from 0.028 grams of Mg is 0.001523 moles

8 0

3 years ago