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PolarNik [594]
2 years ago
6

Please help me with this? :(

Chemistry
1 answer:
Harrizon [31]2 years ago
8 0

Answer:

1. Diagram C.

2. Diagram A.

Explanation:

1. Calcium atom, Ca has 20 protons and 20 electrons. On the other hand, Calcium ion, Ca^2+ has 20 protons and 18 electrons. This is true because the +2 charge on the calcium ion, Ca^2+ indicates that the calcium atom, Ca has loss 2 electrons.

From the above illustration we can say that calcium ion, Ca^2+ has the following:

Proton = 20

Electron = 18

Therefore, diagram C indicates calcium ion, Ca^2+.

2. Fluorine atom, F has 9 protons and 9 electrons. Fluoride ion, F¯ has 9 protons and 10 electrons. This is so because the –1 charge on the fluoride ion, F¯ indicates that the fluorine atom, F has gained 1 electron.

Thus, we can say that the fluoride ion, F¯ has the following:

Proton = 9

Electron = 10

Therefore, diagram A represent fluoride ion, F¯.

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Why do we perform an experiment?
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Answer:

Experiment plays many roles in science. One of its important roles is to test theories and to provide the basis for scientific knowledge. It can also call for a new theory, either by showing that an accepted theory is incorrect, or by exhibiting a new phenomenon that is in need of explanation.

Explanation:

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How does the law of conservation of energy apply to the changes in potential and kinetic energy of a pencil as it falls to the f
antiseptic1488 [7]

The changes in the energy law of conservation of energy is Potential energy is converted to kinetic energy. Kinetic energy is converted into potential energy.

<h3>What is the law of conservation of energy?</h3>

Law of conservation of energy says that energy can neither be created nor destroyed, it just transformed from one form to another.

The energies are kinetic, potential, mechanical, gravitational, electrical, etc.

Thus, the changes in the energy law of conservation of energy is Potential energy is converted to kinetic energy. Kinetic energy is converted into potential energy.

Learn more about law of conservation of energy

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7 0
1 year ago
When should you<br> use a fume hood?
AfilCa [17]

Answer:

if you are working with hazardous materials.

Explanation:

A properly operating and correctly used fume hood can reduce or eliminate exposure to volatile liquids, dusts, and mists. It is advisable to use a laboratory hood when working with all hazardous substances.

4 0
3 years ago
How many moles of argon are contained in 58 L of At at STP?
Harman [31]

Answer:

n = 2.58 mol

Explanation:

Given data:

Number of moles of argon = ?

Volume occupy = 58 L

Temperature = 273.15 K

Pressure = 1 atm

Solution:

The given problem will be solve by using general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

1 atm × 58 L = n × 0.0821 atm.L/ mol.K × 273.15 K

58 atm.L = n × 22.43 atm.L/ mol.

n = 58 atm.L / 22.43 atm.L/ mol

n = 2.58 mol

8 0
2 years ago
If volumes are additive and 253 mL of 0.19 M potassium bromide is mixed with 441 mL of a potassium dichromate solution to give a
Alexxx [7]

Answer:

The concentration of the Potassium Dichromate solution is 0.611 M

Explanation:

First of all, we need to understand that in the final solution we'll have potassium ions coming from KBr and also K2Cr2O7, so we state the dissociation equations of both compounds:

KBr (aq) → K+ (aq) + Br- (aq)

K2Cr2O7 (aq) → 2K+ (aq) + Cr2O7 2- (aq)

According to these balanced equations when 1 mole of KBr dissociates, it generates 1 mole of potassium ions. Following the same thought, when 1 mole of K2Cr2O7 dissociates, we obtain 2 moles of potassium ions instead.

Having said that, we calculate the moles of potassium ions coming from the KBr solution:

0.19 M KBr: this means that we have 0.19 moles of KBr in 1000 mL solution. So:

1000 mL solution ----- 0.19 moles of KBr

253 mL solution ----- x = 0.04807 moles of KBr

As we said before, 1 mole of KBr will contribute with 1 mole of K+, so at the moment we have 0.04807 moles of K+.

Now, we are told that the final concentration of K+ is 0.846 M. This means we have 0.846 moles of K+ in 1000 mL solution. Considering that volumes are additive, we calculate the amount of K+ moles we have in the final volume solution (441 mL + 253 mL = 694 mL):

1000 mL solution ----- 0.846 moles K+

694 mL solution ----- x = 0.587124 moles K+

This is the final quantity of potassium ion moles we have present once we mixed the KBr and K2Cr2O7 solutions. Because we already know the amount of K+ moles that were added with the KBr solution (0.04807 moles), we can calculate the contribution corresponding to K2Cr2O7:

0.587124 final K+ moles - 0.04807 K+ moles from KBr = 0.539054 K+ moles from K2Cr2O7

If we go back and take a look a the chemical reactions, we can see that 1 mole of K2Cr2O7 dissociates into 2 moles of K+ ions, so:

2 K+ moles ----- 1 K2Cr2O7 mole

0.539054 K+ moles ---- x = 0.269527 K2Cr2O7 moles

Now this quantity of potassium dichromate moles came from the respective  solution, that is 441 mL, so we calculate the amount of them that would be present in 1000 mL to determine de molar concentration:

441 mL ----- 0.269527 K2Cr2O7 moles

1000 mL ----- x = 0.6112 K2Cr2O7 moles = 0.6112 M

6 0
3 years ago
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