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aleksandrvk [35]
4 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]4 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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A] 1 N2 + 3 H2 → 2 NH3
Vilka [71]

I haven't done these in some time, so I'm not sure if they are 100% right.

1) 6.3 moles of H2( 2 mol of NH3 / 3  mol of H2)= 4.2 mol of NH3

6.3 moles of H2( 2 mol of NH3/ 3 mol of H2)(17.04 g of NH3/1 mol NH3)= 71.57 g of NH3

2) 2.5 moles of N2(2 mol of NH3/1 mol of N2)= 5 moles of NH3

2.25 moles of N2(2 mol of NH3/ 1 mol of N2)(6.02x10^23 particles/ 1 mol of NH3)= 3.01x10^24 particles of NH3

3) 425 g of NH3(1 mol of NH3/17.04 g NH3)= 24.9 moles of NH3

425 g of NH3(1 mol of NH3/17.04 g of NH3)(1 mol of N2/2 mol of NH3)(28.02 g of N2/1 mol N2)= 349 g of N2

425 g of NH3(1 mol of NH3/17.04 g of NH3)(1 mol of N2/2 mol of NH3)= 12.5 mol of N2

4) 10 moles NH3(3 moles of H2/2 moles of NH3)= 15 moles H2

10 moles NH3(3 mol of H2/2 mol of NH3)(2.02 g of H2/1 mol of H2)= 30.3 g of H2

30.3 g = .0303 liters of H2

8 0
3 years ago
Which statement explains why a molecule of CH4 is nonpolar?
Lerok [7]

Answer:

The geometric shape of a CH4 molecule distributes the charges symmetrically.

Explanation:

The dipole moment is ruled by the compound's geometry and elements electronegativity difference.

Arranging the forces acording to the elements electronegativity difference withing the molecule geometry will yeld the dipole moment.  

If the forces cancel out, it is a nonpolar compound.

If the forces does not cancel out it is a polar compound.

Picture of such analysis for methane is attached.

3 0
4 years ago
Read 2 more answers
In pea plants the trait for green sea pods ( G) is dominant over the trait for yellow seed pods (g) which cross will produce the
alexdok [17]

Answer:

See the answer below

Explanation:

The cross that would produce the maximum number of offspring with green sea pods would be:

1. GG x GG, or

2. GG x gg

The first one would produce all green offspring with homzygous genotypes as follows:

     GG   x   GG

 GG   GG   GG   GG

The second cross would produce all green offspring with heterozygous genotypes as follows:

      GG   x   gg

   Gg   Gg   Gg   Gg

5 0
3 years ago
A bow and arrow that was just pulled back but not yet released has
GREYUIT [131]

Answer:

A potential

Explanation:

potential energy is a kind of energy which rest or stays in one position

7 0
3 years ago
You have a 1.153 g sample of an unknown solid acid, HA, dissolved in enough water to make 20.00 mL of solution. HA reacts with K
Shalnov [3]

Answer:

The concentration of the unknown acid (HA) is 0.434M

The molar mass of HA is 13.3g/mole

Explanation:

DETERMINATION OF MOLARITY OF THE UNKNOWN ACID

CaVa/CbVb = Na/Nb

From the equation of reaction and at equivalence point, Na = Nb = 1

Therefore, CaVa = CbVb

Va (volume of acid solution) = 20mL = 20/1000 = 0.2L

Cb (concentration of KOH) = 0.715M

Vb (volume of KOH) = 12.15mL

Ca (concentration of acid) = CbVb/Va

Ca = 0.715M × 12.15mL/20mL = 0.434M

DETERMINATION OF MOLAR MASS OF HA

Number of moles of acid = concentration of acid × volume of acid solution in liters = 0.434 × 0.2 = 0.0868mole

Molar mass of HA = mass/number of moles = 1.153g/0.0868mole = 13.3g/mole

7 0
4 years ago
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