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aleksandrvk [35]
3 years ago
5

When calcium and magnesium metal are first purchased they are extremely shiny with metallic luster. The metal samples you receiv

ed today however were not very shiny. During the past year these metals have been stored on a shelf until today’s experiment/lab. Why wasn't the calcium metal or the magnesium metal as shiny as the aluminum metal when you first started today’s lab?
Chemistry
1 answer:
gogolik [260]3 years ago
6 0

Answer: The calcium and magnesium metal samples had undergone a chemical reaction (oxidation) with the oxygen present in the air around the shelf to form oxides which caused them to lose their metallic luster overtime. This process is known as tarnishing.

Aluminium also undergoes this process but at a slower rate due to its lower reactivity compared with calcium or magnesium.

Explanation:

Calcium and magnesium belong to the group 2 of the periodic table of metals,generally called alkaline earth metals. They are very reactive and on exposure to air, they react with the oxygen present in air to form <em>coatings/films</em> of calcium oxide and magnesium oxide respectively over the metals. This causes the metals to lose their metallic shine or luster overtime.

Aluminium also undergoes this process generally known as <em>tarnishing</em> forming aluminium oxide but at a slower rate when compared to calcium or magnesium due to their being more reactive than aluminium is.

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At Jim's auto shop, it takes him minutes to do an oil change and minutes to do a tire change. Let be the number of oil changes h
Juli2301 [7.4K]

Answer:

The total time that Jim needs to change x oil changes and y tire changes is less than 180 min.

The time needed for x oil changes is 12 * x.

The time needed for y tire changes is 18 * y.

The total time is the sum of the above times and needs to be less than 180 that is

12 * x + 18 * y < 180 divide both sides of equation by 6

12/6 * x + 18/6*y < 180/6

2*x + 3*y < 30

2*x < 30 - 3*y divide both sides by 2 to get the inequality for x

x < 30/2 - 3/2*y = 15 - 1.5 y < 15 that is x < = 15

2*x + 3*y < 30

3*y < 30 - 2*x divide both sides by 3 to get the inequality for y

y < 30/3 - 2/3 *x = 10 - 2/3*x < 10 that is y < = 10

Also we can write x + y < x+ 3/2 * y < 15.

Explanation:

Jim's can do not more then 5 oil changes and not more then 10 tire changes or all together she can do not more then 15 total of oil and tire changes.

5 0
3 years ago
Can we cover the earth with one mole of pennies?
lara [203]

Answer:

\no

Explanation:

6 0
3 years ago
9. At equilibrium a 2 L vessel contains 0.360
klio [65]

Answer:

Ke = 34570.707

Explanation:

  • H2(g) + Br2(g) → 2 HBr(g)

equilibrium constant (Ke):

⇒ Ke = [HBr]² / [Br2] [H2]

∴ [HBr] = (37.0 mol) / (2 L) = 18.5 mol/L

∴ [Br2] = (0.110 mol) / (2 L) = 0.055 mol/L

∴ [H2] = (0.360 mol) / (2 L) = 0.18 mol/L

⇒ Ke = (18.5 mol/L)² / (0.055 mol/L)(0.18 mol/L)

⇒ Ke = 34570.707

3 0
3 years ago
What is the pH of a solution made by mixing 200 mL of 0.025M HCl and 150 mL of 0.050 M HCl?
seraphim [82]

Answer:

The answer to your question is pH = 1.45  

Explanation:

Data

pH = ?

Volume 1 = 200 ml

[HCl] 1 = 0.025 M

Volume 2 = 150 ml

[HCl] 2 = 0.050 M

Process

1.- Calculate the number of moles of each solution

Solution 1

                Molarity = moles / volume

-Solve for moles

                moles = 0.025 x 0.2

result

               moles = 0.005

Solution 2

               moles = 0.050 x 0.15

-result

                moles = 0.0075

2.- Sum up the number of moles

Total moles = 0.005 + 0.0075

                   = 0.0125

3.- Sum up the volume

total volume = 200 + 150

                     350 ml or 0.35 l

4.- Calculate the final concentration

Molarity = 0.0125 / 0.35

              = 0.0357

5.- Calculate the pH

pH = -log [H⁺]

-Substitution

pH = -log[0.0357]

-Result

pH = 1.45    

8 0
3 years ago
Chemistry acids and bases
Ket [755]

Answer:

Imma just say acids have more acidity and bases have lower acidity...

4 0
3 years ago
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