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3 years ago

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The titration of 25.0 ml of an iron(ii) solution required 18.0 ml of a 0.205 m solution of dichromate to reach the equivalence p

oint. what is the molarity of the iron(ii) solution?

1 answer:

sasho [114]3 years ago

6 0

The formula of this is : MV = MV or Molarity × Volume = Molarity × Volume. So you do:
25X = 18×.205=.1476M

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Rolls of foil are 300mm wide and 2.020mm thick. (The density of foil is 2.7 g/cm^3). What maximum length of foil can be made fro

horrorfan [7]

Answer: 8556 mm, or 855.6 cm (8560 mm to 3 sig figs)

Explanation: Convert mm to cm by dividing by 10 (1cm/10mm)

Find the area of the foil face in cm^2 (30cm*0.2020cm) = 0.606 cm^2

Calculate the volume occupied by 1.40 kg of foil in cm^3. 1.40kg = 1400g

1.400g/(2.7 g/cm^3) = 518.5 cm^3 for 1.40 kg Au

Volume = Area (of the face) * Length

We want Length:

Length = Volume/Area

L = (518.5 cm^3/0.606 cm^2)

L = 855.6 cm (8556 mm) Round to 3 sig figs (856 cm and 8560 mm)

5 0

3 years ago

Menthol, the substance we can smell in mentholated cough drops, is composed of C, H, and O. A 0.1005 g sample of menthol is comb

Bogdan [553]

<u>Answer:</u> The molecular formula for the menthol is $C_{10}H_{20}O$

<u>Explanation:</u>

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=0.2829g$

Mass of $H_2O=0.1159g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

<u>For calculating the mass of carbon:</u>

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 0.2829 g of carbon dioxide, $\frac{12}{44}\times 0.2829=0.077g$ of carbon will be contained.

<u>For calculating the mass of hydrogen:</u>

In 18g of water, 2 g of hydrogen is contained.

So, in 0.1159 g of water, $\frac{2}{18}\times 0.1159=0.0129g$ of hydrogen will be contained.

Mass of oxygen in the compound = (0.1005) - (0.077 + 0.0129) = 0.0106 g

To formulate the empirical formula, we need to follow some steps:

<u>Step 1:</u> Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{0.077g}{12g/mole}=0.0064moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.0129g}{1g/mole}=0.0129moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{0.0106g}{16g/mole}=0.00066moles$

<u>Step 2:</u> Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.00066 moles.

For Carbon = $\frac{0.0064}{0.00066}=9.69\approx 10$

For Hydrogen = $\frac{0.0129}{0.00064}=19.54\approx 20$

For Oxygen = $\frac{0.00066}{0.00066}=1$

<u>Step 3:</u> Taking the mole ratio as their subscripts.

The ratio of C : H : O = 10 : 20 : 1

Hence, the empirical formula for the given compound is $C_{10}H_{20}O_1=C_{10}H_{20}O$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is :

$n=\frac{\text{molecular mass}}{\text{empirical mass}}$

We are given:

Mass of molecular formula = 156.27 g/mol

Mass of empirical formula = 156 g/mol

Putting values in above equation, we get:

$n=\frac{156.27g/mol}{156g/mol}=1$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(1\times 10)}H_{(1\times 20)}O_{(1\times 1)}=C_{10}H_{20}O$

Thus, the molecular formula for the menthol is $C_{10}H_{20}O$

4 0

3 years ago

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How many moles of carbon are there in a 0.70 g (3.5 carat) diamond?

maksim [4K]

Answer:

3.5 x 10^22 moles of carbon are there in a 0.70 g (3.5 carat) diamond.

Explanation:

In case of diamond, the number of atoms is the same as the number of molecules.

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4 years ago

One hundred million copper atoms are arranged in a line. Which is a reasonable estimate for the length of this line?

Anettt [7]

The size of an atom is roughly 10^-10 metres

10^-10 • 100,000,000 = 0.01 metres

Since 1 metre = 100 centimetre

0.01 x 100 = 1 centimetre

There’s your answer

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3 years ago

If hydrochloric acid has a [H+] of 1.2 x 10-2 M, what is the pH?<br> 1.9<br> 0 1<br> 1.2<br> O<br> 8

Vanyuwa [196]

Answer:

<h2>1.9</h2>

Explanation:

The pH of a solution can be found by using the formula

$pH = - log [ {H}^{+} ]$

From the question we have

$pH = - log(1.2 \times {10}^{ - 2} ) \\ = 1.920818...$

We have the final answer as

<h3>1.9</h3>

Hope this helps you

7 0

3 years ago

Read 2 more answers