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Nesterboy [21]
3 years ago
13

Will mark as Brainliest.

Chemistry
1 answer:
viktelen [127]3 years ago
8 0
B) Bohr's Atomic Model
You might be interested in
A compound is 42.9% C, 2.4% H, 16.7% N, and 38.1% O, by mass. Addition of 6.45 g of this compound to 50.0 mL benzene, lowers the
Romashka [77]

This is an incomplete question, here is a complete question.

A compound is 42.9% C, 2.4% H, 16.7% N and 38.1% O by mass. Addition of 6.45 g of this compound to 50.0 mL benzene, C₆H₆ (d= 0.879 g/mL; Kf= 5.12 degrees Celsius/m), lowers the freezing point from 5.53 to 1.37 degrees Celsius. What is the molecular formula of this compound?

Answer : The molecular of the compound is, C_6H_4N_2O_4

Explanation :

First we have to calculate the mass of benzene.

\text{Mass of benzene}=\text{Density of benzene}\times \text{Volume of benzene}

\text{Mass of benzene}=0.879g/mL\times 50.0mL=43.95g

Now we have to calculate the molar mass of unknown compound.

Given:

Mass of unknown compound (solute) = 6.45 g

Mass of benzene (solvent) = 43.95 g  = 0.04395 kg

Formula used :  

\Delta T_f=K_f\times m\\\\\Delta T_f=K_f\times\frac{\text{Mass of unknown compound}}{\text{Molar mass of unknown compound}\times \text{Mass of benzene in Kg}}

where,

\Delta T_f = change in freezing point  = 5.53-1.37=4.16^oC

\Delta T_s = freezing point of solution

\Delta T^o = freezing point of benzene

Molal-freezing-point-depression constant (K_f) for benzene = 5.12^oC/m

m = molality

Now put all the given values in this formula, we get

4.16^oC=(5.12^oC/m)\times \frac{6.45g}{\text{Molar mass of unknown compound}\times 0.04395kg}

\text{Molar mass of unknown compound}=180.6g/mol

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 42.9 g

Mass of H = 2.4 g

Mass of N = 16.7 g

Mass of O = 38.1 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of N = 14 g/mole

Molar mass of O = 16 g/mole

Step 1 : convert given masses into moles.

Moles of C = \frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{42.9g}{12g/mole}=3.575moles

Moles of H = \frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{2.4g}{1g/mole}=2.4moles

Moles of N = \frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{16.7g}{14g/mole}=1.193moles

Moles of O = \frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{38.1g}{16g/mole}=2.381moles

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = \frac{3.575}{1.193}=2.99\approx 3

For H = \frac{2.4}{1.193}=2.01\approx 2

For N = \frac{1.193}{1.193}=1

For O = \frac{2.381}{1.193}=1.99\approx 2

The ratio of C : H : N : O = 3 : 2 : 1 : 2

The mole ratio of the element is represented by subscripts in empirical formula.

The Empirical formula = C_3H_2N_1O_2

The empirical formula weight = 3(12) + 2(1) + 1(14) + 2(16) = 84 gram/eq

Now we have to calculate the molecular formula of the compound.

Formula used :

n=\frac{\text{Molecular formula}}{\text{Empirical formula weight}}

n=\frac{180.6}{84}=2

Molecular formula = (C_3H_2N_1O_2)_n=(C_3H_2N_1O_2)_2=C_6H_4N_2O_4

Therefore, the molecular of the compound is, C_6H_4N_2O_4

3 0
3 years ago
A silver necklace has a density of 10.5 g/mL and a volume of 1.5 mL. What is the mass of the silver necklace?
melamori03 [73]

Answer:

15.75g

Explanation:

Rearrange the formula: density = mass/volume, so that mass is the subject: mass = density × volume

Now substitute (plug in) the known values into the formula:

mass = 10.5 × 1.5 ⇒ mass = 15.75g

The mass of the silver necklace is 15.75g

Hope this helps!

4 0
2 years ago
Which of the following statements related to S N1 reactions is not true? - The heterolysis of a bond between atoms which do not
Varvara68 [4.7K]

Answer:

The charged carbon atom of a carbocation has a complete octet of valence shell electrons

Explanation:

A charged carbon atom of a carbocation has a valence shell that is not filled, <u>that's why it acts as an electrophile (or a Lewis base)</u>. This unfilled valence shell is also the reason of the nucleophilic attack that takes place during the second step of a SN1 reaction.

6 0
3 years ago
7. Iron combines with 4.00 g of Copper (11) nitrate to form 6.01 g of Iron (I) nitrate and 0.400 g copper
olga55 [171]

Answer:

222325332

Explanation:

4 0
2 years ago
Read 2 more answers
Which formula correctly represents antinomy trichloride?<br> SnS2<br> SnCl3<br> SbCl2<br> SbCl3
max2010maxim [7]

Answer:

SbcI3

Explanation:

The symbol of antimony is 'Sb'.

The symbol of chlorine is 'Cl'

First write down the symbol of the first element.

Use the prefix to determine the atoms of first element. If there is no prefix on element then there is only 1 atom.

Now write down the symbol of the second element.

Use the prefix to determine the atoms of second element.

Use prefix as 'mono' for '1', 'di' for '2', 'tri' for '3' and so on.

3 0
2 years ago
Read 2 more answers
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