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antiseptic1488 [7]
3 years ago
7

15. Name the element that has 3 energy levels and 3 valence electrons. *

Chemistry
1 answer:
uysha [10]3 years ago
6 0

Answer:

aluminium ..............

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Determine the molarity of a solution formed by dissolving 97.7 g libr in enough water to yield 750.0 ml of solution.
rewona [7]

Answer:

1.5 M.

Explanation:

  • Molarity (M) is defined as the no. of moles of solute dissolved in a 1.0 L of the solution.

<em>M = (no. of moles of LiBr)/(Volume of the solution (L).</em>

<em></em>

∵ no. of moles of LiBr = (mass/molar mass) of LiBr = (97.7 g)/(86.845 g/mol) = 1.125 mol.

Volume of the solution = 750.0 mL = 0.75 L.

∴ M = (no. of moles of luminol)/(Volume of the solution (L) = (1.125 mol)/(0.75 L) = 1.5 M.

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3 years ago
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What is related to the energy of motion of the particles of matter?
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The Kinitec Molecular Theory of Matter 
Yes Kninetic energy
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At 63.5 C the vapor pressure of H2O is 175 torr and that of ethanol is 400 torr. A solution is made by adding equal masses of H2
xxTIMURxx [149]

Answer:

Moel fraction of ethanol in the solution = 0.28

Vapor pressure of the solution = 238 torr

Mole fraction of ethanol in the vapor = 0.47

Explanation:

Let's use 100 g of each substance as a calculus basis. Knowing that the molar mass of water is 18 g/mol and the molar mass of ethanol is 46 g/mol, the number of moles (n = mass/molar mass) of each one is:

nw = 100/18 = 5.56 mol

ne= 100/46 = 2.17 mol

The total number of moles is 7.73 mol, so the mole fraction of ethanol is

2.17/7.73 = 0.28

The mole fraction of water must be 0.72, so if we assume that the solution is ideal, by the Raoult's law, the solution vapor pressure is the sum of the multiplication of the mole fraction by the vapor pressure of each substance, thus:

P = 0.28*400 + 0.72*175

P = 238 torr

The partial pressure of each substance can be found by the multiplication of the molar fraction by the vapor pressure, thus:

Pw = 0.72*175 = 126 torr

Pe = 0.28*400 = 112 torr

To know the number of moles that is vaporized above the solution, we may use the ideal gas law:

PV = nRT

P/n = RT/V

R is the gas constant, T is the temperature and V is the volume, so they are the same for both water and ethanol, thus

Pw/nw = Pe/ne

126/nw = 112/ne

ne = (112/126)*nw

ne = 0.89nw

So, the mole fraction of ethanol is:

ne/(ne + nw) = 0.89nw/(0.89nw + nw) = 0.89/1.89 = 0.47

4 0
3 years ago
Is this example of a direct proportion or an inverse proportion?
ivanzaharov [21]

Answer:

Inverse proportion occurs when one value increases and the other decreases. For example, more workers on a job would reduce the time to complete the task. They are inversely proportional.

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Distance form the sun makes no difference to the temperature of a planet.<br><br> True<br> False
ELEN [110]

Answer: false

Explanation:

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