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3 years ago

If 11.87 grams of sand (SiO2) were contained in the mixture, how many atoms of oxygen were in the mixture?

Chemistry

1 answer:

ozzi3 years ago

6 0

Answer:

2.38x10²³ atoms oxygen

Explanation:

To solve this question we need to convert the mass of sand to moles using its molar mass (Molar mass SiO₂ = 60.08g/mol). Twice these moles are the moles of Oxygen and using Avogadro's number we can find the amount of atoms of Oxygen in the mixture:

Moles SiO₂:

11.87g * (1mol / 60.08g) = 0.1976moles SiO₂

Moles Oxygen:

0.1976moles SiO₂* 2 = 0.3951moles oxygen

Atoms oxygen:

0.3951moles oxygen * (6.022x10²³atoms / 1mol O₂) =

<h3>2.38x10²³ atoms oxygen</h3>

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3 years ago

What mass of powdered drink mix is needed to make a 0.5 M solution of 100 mL?

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Answer:

There is 17,114825 g of powdered drink mix needed

Explanation:

Step 1 : Calculate moles

As given, the concentration of the drink is 0.5 M, this means 0.5 mol / L

Since the volume is 100mL, we have to convert the concentration,

⇒0.5 / 1 = x /0.1 ⇒ 0.5* 0.1 = x = 0.05 M

This means there is 0.05 mol per 100mL

Step 2 : calculate mass of the powdered drink

here we use the formula n (mole) = m(mass) / M (Molar mass)

⇒ since powdered drink mix is usually made of sucrose (C12H22O11) and has a molar mass of 342.2965 g/mol.

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To find the mass, we isolate it ⇒0.05 mol * 342.2965 g/mol = 17,114825g

There is 17,114825 g of powdered drink mix needed

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3 years ago

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How did Henry Moseley revise Mendeleev's periodic table? (Please answer A.S.A.P.)

CaHeK987 [17]

If you give it a good search, the most used answer would probably be as follows,

In 1914 Henry Moseley found a relationship between an element's X-ray wavelength and its atomic number (Z), and therefore rearranged the table by nuclear charge / atomic number rather than atomic weight. Before this discovery, atomic numbers were just sequential numbers based on an element's atomic weight. Moseley's discovery showed that atomic numbers had an experimentally measurable basis.

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3 years ago

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tensa zangetsu [6.8K]

Answer:

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Explanation:

This reaction is an example of the dehydration of cyclic alcohols. The reaction proceeds in the following steps;

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2) the water molecule, which a good leaving group now leaves yielding a carbocation. This now leaves a cyclohexane carbocation which is highly reactive.

3) A water molecule now abstracts a proton from the carbon adjacent to the carbocation leading to the formation of cyclohexene and the regeneration of the acid catalyst. This is an E1 mechanism because it proceeds via a carbocation intermediate and not a concerted transition state, hence the answer.

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