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Elodia [21]
3 years ago
7

Which statement about the periodic table is true?

Chemistry
1 answer:
dedylja [7]3 years ago
8 0

Answer

Two different elements have similar chemical properties when they have the same number of valence electrons in their outermost energy level. ... Elements in the same column of the Periodic Table have the same number of valence electrons – that's why they have similar chemical properties.

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When 240 mg of a certain molecular compound X are dissolved in 35.0 g of dibenzyl ether ((C6H5CH2)2O), the freezing point of the
DedPeter [7]

Answer: MM = 16.55 g/mol

Explanation: <u>Freezing</u> <u>point</u> <u>depression</u> is a phenomena that explains why adding a solute to a solvent decreases the solvent freezing point: when a substance begins to freeze, its molecules slows down and rearrange itself forming a solid. If a solute is added, the molecules from the solvent interfere in the formation of the solid. To guarantee the transformation, the solution has to cooled down even more.

Freezing point and molality concentration is related by

\Delta T=T_{f}_{(solvent)}-T_{f}_{(solution)}=K_{f}.m

where

ΔT is freezing point depression

T_{f}_{(solvent)} and T_{f}_{(solution)} are freezing point of solvent and solution, respectively

K_{f} is freezing point depression constant

m is molality concentration

<u />

Dibenzyl ether is the solvent and has the following properties: K_{f}= 6.27 and T_{f} = 3.6°C.

Molality concentration is

m=\frac{T_{(solvent)}-T_{(solution)}}{K_{f}}

m=\frac{3.6-1}{6.27}

m = 0.415

<u>Molality</u> <u>concentration</u> is moles (n) of solute dissolved in a mass, in kilogram, of solvent.

m=\frac{moles}{mass(kg)}

n = m(mass of solvent in kg)

n = 0.415(0.035)

n = 0.0145

<u>Molar</u> <u>mass</u> (M) is the weight of one sample mole and can be calculated as

n=\frac{m}{M}

M = \frac{m}{n}

m in grams

Molar mass of compound X is

M=\frac{0.24}{0.0145}

M = 16.55

<u>Molar mass of molecular</u><u> compound X is 16.55g/mol</u>

3 0
3 years ago
Which of the following structers is formed when fertilization occurs
kaheart [24]
I believe the answer would be C
5 0
4 years ago
How are the digestive system and the urinary system similar?
Olenka [21]

Answer:

While the digestive system collects and removes undigested solids, the excretory system filters compounds from the blood stream and collects them in urine. They are closely connected in controlling the amount of water in your body.

Explanation:

4 0
3 years ago
Table salt contains 39.33 g of sodium per 100 g of salt. The U.S. Food and Drug Administration (FDA) recommends that adults cons
IrinaVladis [17]
 <span>First set up the equation 39.33g/100g = x/1.28g and that'll give you how much sodium is in each 100g of the mix. 

39.33g *1.28g= 100g * x 
x = 0.503424g 
x = Amount of sodium per 100g of the mix 

Now 2.4g / 0.503424 = 4.7674 
Multiply by 100 and you get 476.7353g</span>
4 0
3 years ago
Read 2 more answers
10.0 g of gaseous ammonia and 6.50 g of oxygen gas are introduced into a previously evacuated 5.50 L vessel. If the ammonia and
Shalnov [3]

Answer:

The density is 3g/L

Explanation:

The reaction that occurs in the vessel is:

4 NH₃ + 5 O₂ → 4 NO + 6 H₂O

10,0g of NH₃ are:

10,0g * \frac{1mol}{17,031g} = 0,587 moles

6,50 g of O₂ are:

6,50g * \frac{1mol}{32g} = 0,203 moles

For a complete reaction of O₂ there are necessaries:

0,203 mol * \frac{4molNH_{3}}{5molO_{2}}= 0,163 moles of NH_{3}

O₂ is limiting reactant. The excess moles of NH₃ are:

0,587 - 0,163 = <em>0,424 moles of NH₃</em>

These moles are:

0,424mol * \frac{17,031g}{1mol} = <em>7,22g of NH₃</em>

Knowing O₂ is limiting reactant, mass of NO and H₂O are:

0,203molO_{2}*\frac{4molNO}{5molO_{2}}*\frac{30,01g}{1molNO} = <em>4,87g of NO</em>

0,203molO_{2}*\frac{6molH_{2}O}{5molO_{2}}*\frac{18,02g}{1molH_{2}O} = <em>4,39g of H₂O</em>

The total mass is: 7,22g + 4,87g + 4,39g = 16,48g ≡ <em>16,5g </em>

<em>-</em><em>The same mass add in the first. By matter conservation law-</em>

As vessel volume is 5,50L, density is:

16,5g/5,50L = <em>3g/L</em>

I hope it helps!

7 0
4 years ago
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