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2 years ago

If an atom has 15 protons, 14 neutrons, and 18 electrons, what is the atom's electrical charge?

1 answer:

6 0

Answer:By referring to a periodic table or table of elements, we see that phosphorus (symbol P) has an atomic number of 15. Thus, each atom has 15 protons. The mass number of the ion is 15 + 16 = 31. Because the ion has 15 protons and 18 electrons (three more electrons than protons), its net charge is 3-.

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How would you separate the following ions by selective precipitation Ag + , Pb 2+, Cu 2+.

Lemur [1.5K]

Answer:

we cannot vduurggruuriirru**

4 0

3 years ago

A ball is equipped with a speedometer and launched straight upward. The speedometer reading four seconds after launch is shown a

Andrew [12]

Answer:

Question 1: 1 s after the motion starts

Question 2: 0 (just when the motion starts)

Explanation:

You will need to work with approximates values because the precision of the speedometers is low and you are requested to find approximate times.

1. From the speedometer shown at the right.

You can obtain how long the ball has been falling from the highest altitute it reached using the speed of 10 m/s shown by the speedometer at the right.

Free fall equation: Vf = Vo - gt

Vo = 0 ⇒ Vf = gt ⇒ t = Vf / g

For this problem, I recommend to work with a rough estimate of g: g = 10 m/s² ( I will tell you why soon)/

t = [10 m/s] / [10 m/s²] = 1 s

That is the time falling. Since four seconds after launch have elapsed, the upward time was 3 seconds. This will let you to calculate the launching speed.

2. Time when the speedometer displays a reading of 20 m/s

First, calculate the launching speed:

Vf = Vo - gt

Since the ball was 3 seconds going upward and the speed at the maximum altitude is 0 you get:

0 = Vo - gt

Vo = gt = 10 m/s² × 3 s = 30 m/s

Now, use the initial velocity to calculate when the ball is going upward with the speedometer reading is 20 m/s

20 m/s = 30 m/s - 10 m/s² × t

t = [ 30 m/s - 20 m/s] / [10 m/s²] = 1 s

Thus, the first answer is t = 1 s.

3. Time when the speedometer displays a reading of 30 m/s

This is the same speec estimated for the launching: 30 m/s.

So, this reading corresponds to the moment when the ball was launched.

Thus time is 0, i.e. it is the same instant of the launch.

If you had worked with g = 9.80 m/s², the time had been negative. This is due to the precision of the instruments.

That is why I recommended to work with g = 10 m/s².

6 0

3 years ago

. Guillermo was finding it difficult to walk up the steps to his family’s apartment. His doctor thinks that his cells might not

morpeh [17]

Answer:

Because oxygen is the combustion fuel and glucose is the substrate needed for synthesis of energy as ATPs during cellular respiration.Therefore Guillermo lacks enough energy as ATPs in her body cells, especially skeletal muscles cells to complete the task of ascending the s steps.

For all the mitochondrial in cells(sites of energy production) to receive needed glucose,and other metabolites needed for energy synthesis; an efficient transport system is needed, so that these materials are available immediately, in required amount. This system is called circulatory system.

And for the the supply of combustion fuel (oxygen) needed for the completion of the ATP synthesis mechanisms; respiratory systems which convey oxygen from the external environments to the circulatory system through breathing mechanisms, for distribution is needed.

Thus the doctor needs to test both the circulatory and respiratory systems.

Explanation:

4 0

3 years ago

What is the expected value for the heat of sublimation of acetic acid if its heat of fusion is 10.8 kJ/mol and its heat of vapor

Dennis_Churaev [7]

Answer:

35.1 kJ/mol is the expected value for the heat of sublimation of acetic acid.

Explanation:

$CH_3COOH(l)\rightarrow CH_3COOH(g)$ ..[1]

Heat of vaporization of acetic acid = $H^o_{vap}=24.3 kJ/mol$

$CH_3COOH(s)\rightarrow CH_3COOH(l)$ ..[2]

Heat of fusion of acetic acid = $H^o_{fus}=10.8 kJ/mol$

Heat of sublimation of acetic acid = $H^o_{sub}=?$

$CH_3COOH(s)\rightarrow CH_3COOH(g)$ ..[3]

[1] + [2] = [3] (Hess's law)

$H^o_{sub}=H^o_{vap}+H^o_{fus}$

$=24.3 kJ/mol+10.8 kJ/mol=35.1 kJ/mol$

35.1 kJ/mol is the expected value for the heat of sublimation of acetic acid.

5 0

3 years ago

The lowest value of the henry's law for methane gas (ch4) will be obtained with __________ as the solvent and a temperature of _

NikAS [45]

The lowest value of the henry's law for methane gas (CH₄) will be obtained with H₂O as the solvent and a temperature of 349 K.

Henry's law: This law states that at a constant temperature, the amount of a gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas that in equilibrium with that liquid.

Mathematically it can be written as:

$C_{g}=k\times P_{g}$

So, for the methane gas , lowest value of the henry's law obtained at 349 K and with H₂O as the solvent.

3 0

3 years ago