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3 years ago

Elements in Group 4A

Chemistry

1 answer:

steposvetlana [31]3 years ago

6 0

Answer:

helium hydrogen

Explanation:

lithium beryllium bottom carbon

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The principal component of mothballs is naphthalene, a compound with a molecular mass of about 130 amu, containing only carbon a

DIA [1.3K]

Answer:

Empirical formula = C5H4

Molecular formula = C10H8

Explanation:

When the 3000 mg of naphthalene are burned they produce 10.3 mg of CO2. Knowing the unbalanced equation of the combustion of naphthalene, we have:

CxHy + O2 = CO2 + H2O

We calculate the molar composition of the sample. We look for the molecular weights in the periodic table:

CO2 = 12,011 + 2 (15,999) = 44,009 g

Mol C = 10.3 mg * (1 mol CO2 / 44.009 g CO2) * (1 mol C / 1 mol CO2) = 0.234 mmol C

Mass C = 0.234 mmol C * (12.011 g C / 1 mol C) = 2.8105 mg C

Mass H = 3 mg - 2.8105 mg = 0.1895 mg H

Mol H = 0.1895 mg H * (1 mol H / 1,008 g H) = 0.188 mmol H

To calculate the empirical formula, we must divide the number of moles of each element by the smallest number of moles, in this case, of hydrogen:

C = 0.2340 mmol C / 0.1895 mol H = 1.25

H = 0.1895 mmol H / 0.1895 mmol H = 1

We multiply the coefficients by 4, and we have the empirical formula:

C1.25 * 4H1 * 4 = C5H4

The molecular formula is equal to (C5H4)m, where m is calculated by the molecular and empirical mass ratio, as follows:

Empirical mass = (5 * 12.011) + (4 * 1.008) = 64.09 g

m = 130 g / 64.09 g = 2.02 = 2

Therefore we have the molecular formula:

(C5H4)2 = C10H8

4 0

3 years ago

We can preserve natural resources by

DedPeter [7]

The answer is c, relying on renewable energy sources

3 0

3 years ago

PLS HELP-CHEMISTRY: What is the molar concentration of an ammonia solution in which there are 0.1557 grams

harina [27]

Answer: M = 0.036 M

Explanation: Solution attached:

First convert mass of NH3 to moles

Next convert volume in mL to L

Use the formula for Molarity

M = n / L

4 0

3 years ago

A sample of the chiral molecule limonene is 62% enantiopure. what percentage of each enantiomer is present? what is the percent

ikadub [295]

The mixture contains 62 % one isomer and 38 % the enantiomer.

Let’s say that the mixture contains 62 % of the (R)-isomer.

Then % (S) = 100 % -62 % = 38 %

ee = % (R) - % (S) = 62 % -38 % = 24 %

6 0

3 years ago

Read 2 more answers

A student pours 44.3 g of water at 10Â°C into a beaker containing 115.2 g of water at 10Â°C. What are the final mass, temperatur

Agata [3.3K]

Answer:

Final mass = 159.5 g

Final temperature = 10 C

Final density = 1.00 g/ml

Explanation:

Given:

Beaker 1:

Mass of water = 44.3 g

Temperature = 10 C

Beaker 2:

Mass of water = 115.2 g

Temperature = 10 C

Density of water at 10C = 1.00 g/ml

To determine:

The final mass, temperature and density of water

Calculation:

$Final\ mass\ of \ water = Beaker\ 1 + Beaker\ 2 = 44.3 + 115.2 = 159.5 g$

Since there is no change in temperature, the final temperature will be 10 C

Density of a substance is an intensive property i.e. it is independent of the mass. Hence the density of water will remain constant i.e. 1.00 g/ml

3 0

3 years ago