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3 years ago

How many oxygen atoms are in 2.80 g of quartz?

1 answer:

4 0

The chemical formula for quartz is SiO₂
Percentage by mass of oxygen = (2 x 16) x 100 / (28 + 2 x 16)
Percentage by mass of oxygen = 53.3%

Mass of oxygen in sample = 0.533 x 2.8
Mass of oxygen = 1.49 grams

Moles of oxygen = 1.49 / 16
Moles = 0.093

One mole contains 6.02 x 10²³ particles
Thus, the atoms of oxygen:
0.093 x 6.02 x 10²³
= 5.6 x 10²²

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When science is used to create a new instrument, such as a cell phone, we say that a new ___________ has been developed.

kari74 [83]

Is it Technology? What have you already tried?

3 0

3 years ago

What is the molecular formula of a compound that is composed of 94.1% O and 5.9% H with a molar mass of 34g

elena-s [515]

Answer:

B. 67.6/Hg(200.5)= .337. 10.8/S(32.1)= .336. 21.6/O(16)= 1.35--> .337/.336= 1 .336/.336= 1 1.35/.336= 4. Formula= HgSO4

Explanation:

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3 years ago

The reaction of hydrogen(g) with fluorine(g) to form hydrogen fluoride(g) proceeds as follows: H2(g) + F2(g) 2 HF(g) When 0.647

Nata [24]

Answer: The value of $\Delta H$ for the reaction will be -537 kJ

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of hydrogen gas = 0.647 g

Molar mass of hydrogen gas = 2 g/mol

Putting values in above equation, we get:

$\text{Moles of hydrogen gas}=\frac{0.647g}{2g/mol}=0.324mol$

We are given:

Energy released for 0.324 moles of hydrogen reacted is 174 kJ

For the given chemical reaction:

$H_2(g)+F_2(g)\rightarrow 2HF(g)$

By Stoichiometry of the reaction:

When 0.324 moles of hydrogen gas is reacted, the energy evolved is 174 kJ

So, when 1 mole of hydrogen gas will react, the energy evolved will be = $\frac{174kJ}{0.324mol}\times 1mol=537kJ$

Sign convention of heat:

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

Hence, the value of $\Delta H$ for the reaction will be -537 kJ

6 0

3 years ago

Liquid in a graduated cylinder has a volume of 70 mL. You put a small solid ball into the cylinder, and the height of the liquid

emmasim [6.3K]

Yes sir

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3 years ago

What happens when stress builds at faults? Select three options

Stels [109]

Answer:

When Stress builds up at faults, the 3 options that are correct and can happen

- Rock can bend and break;

- Earthquakes develop at Earth's surface

- Forces affect Earth's rocks

Explanation:

This is a Geography question

- Rock can bend and break

When Stress builds up at faults, it leads to a geologic activity that causes a lot of pressure that lead to the movement of the earth's crust. The movement creates such intense pressure on the rocks, that, with time, they twist, bend, and break due to this pressure.

- Earthquakes develop at Earth's surface

As explained earlier, this intense pressure can lead to rocks breaking, as these rocks break inside the earth's crust, the gaps that come into play after the breaking of the rocks causes the remaining rocks to adjust, releasing a lot of force, and subsequently creating earthquakes.

- Forces affect Earth's rocks

As explained earlier, the forces resulting from these intense pressures, affect the earth's rocks. They move them both vertically and horizontally, change their shape and eventually break them.

Hope this Helps!!!

8 0

3 years ago