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3 years ago

How many moles are in 3.4 x 10-7 grams of silicon dioxide?

Chemistry

2 answers:

Andreyy893 years ago

8 0

Answer:

$1.13X10^{-8}mol$

Explanation:

The molecular formula of silicon dioxide is : SiO₂

There are two oxygen atoms and one silicon atom.

The atomic mass of oxygen = 16 g/mol

The atomic mass of silicon = 28 g/mol

So the molar mass of silicon dioxide = 28 + 2(16) = 60 g/mol

Given the mass of silicon dioxide = $3.4X10^{-7}$

$moles=\frac{mass}{molarmass}=\frac{3.4X10^{-7}}{30}=1.13X10^{-8}mol$

matrenka [14]3 years ago

3 0

Molar mass is 28+32 = 60
So take 3.4 x 10^-7/60 and get about 5.7 x 10^-9

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When 6.040 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 18.95 grams of CO2 and 7.759 grams of H

algol [13]

Answer: The empirical formula is $CH_2$ and molecular formula is $C_4H_8$

Explanation:

We are given:

Mass of $CO_2$ = 18.95 g

Mass of $H_2O$ = 7.759 g

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

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

So, in 18.59 g of carbon dioxide, = $\frac{12}{44}\times 18.59=5.07g$ of carbon will be contained.

For calculating the mass of hydrogen:

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

So, in 7.759 g of water, = $\frac{2}{18}\times 7.759=0.862g$ of hydrogen will be contained.

Mass of C = 5.07 g

Mass of H = 0.862 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{5.07g}{12g/mole}=0.422moles$

Moles of H= $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.862g}{1g/mole}=0.862moles$

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

For C = $\frac{0.422}{0.422}=1$

For H = $\frac{0.862}{0.422}=2$

The ratio of C : H = 1: 2

Hence the empirical formula is $CH_2$ .

The empirical weight of $CH_2$ = 1(12)+2(1)= 14 g.

The molecular weight = 56.1 g/mole

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight }}{\text{Equivalent weight}}=\frac{56.1}{14}=4$

The molecular formula will be= $4\times CH_2=C_4H_8$

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3 years ago

PPLLLSSSSSSS HELLLPPP!!!!! What is runoff?

mr Goodwill [35]

Answer:

runoff is he draining away of water (or substances carried in it) from the surface of an area of land, a building or structure, etc.

Explanation:

4 0

3 years ago

Read 2 more answers

A device that does work with only one movement and changes the size or direction of a force is a(n) ____.

worty [1.4K]

Answer:

A device that does work with only one movement and changes the size or direction of a force is a simple machine.

Explanation:

For applying force, any used basic mechanical devices are simple machines.
Simple machine changes the direction as well as the amplitude of the applied force i.e. we can increase or decrease the magnitude of the force.
A simple machine is the most basic mechanism to use the force as we need in big mechanical machines.
Some of the examples of simple machines are inclined plane, lever, wedge, wheel and axle, pulley, and screw.

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3 years ago

A gas has a volume of 240 mL and a pressure of 0.99 atm. If the pressure is decreased to 0.951 atm, what is the new volume of th

irakobra [83]

V2 = 250 ml

Explanation:

Given:

P1 = 0.99 atm. V1 = 240 ml

P2 = 0.951 atm. V2 = ?

We can use Boyle's law to solve for V2

P1V1 = P2V2

V2 = (P1/P2)V1

= (0.99 atm/0.951 atm)(240 ml)

= 250. ml

6 0

3 years ago

If the volume of a solid is 100cm^3 and its mass is 400 g, what is it’s density

Aleksandr-060686 [28]

Answer:

The answer to your question is: density = 4 g/cm³

Explanation:

Data

Volume = 100 cm³

Mass = 400 g

Density = ?

Formula

density = mass/volume

substitution

density = 400/100 = 4 g/cm³

4 0

3 years ago