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antiseptic1488 [7]
3 years ago
14

Determine the percent composition of potassium dichromate, K2Cr2O7.

Chemistry
1 answer:
bulgar [2K]3 years ago
4 0

Answer:

Option E is the correct one

Explanation:

K₂Cr₂O₇ → Potassium dichromate

A ionic salt which its molar mass is 294.18 g/m

It is composed by 2 mol of K, 2 mol of Cr and 7 mol of O

2 mol of K = 78.2 g

2 mol of Cr = 104 g

7 mol of O = 112 g

In 294.2 g of compound we have __78.2 g K __ 104 g Cr ___ 112 g O

Let's calculate the percent

(78.2 / 294.2) .100 = 26.59% K

(104 / 294.2) .100 = 35.35% Cr

(112 / 294.2) . 100 = 38.06 % O

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Cholesterol is  a sterol, it is a type of lipid molecule, and is biosynthesized by all animal cells. Total cholesterol level lesser than 200 milligrams per deciliter (mg/dL) is considered desirable for an adult. The standard unit used for any substance is gram per liter. However sometimes the concentration can also be expressed in terms of mg per deciliter. In this context 1 gram per liter is equal to 100 milligram per deciliter.

Thus 1.85 gram per liter is equal to 185 mg per deciliter. So 1.85 g/L is equivalent to 185mg per deciliter.

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3 years ago
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How many valence electrons do alkali metals have?
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1 valence electron in alkali metals.
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How would I complete and balance the equation <br> Mg + Br2 &gt;
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Which forms when a humid air mass rises into a cooler temperature area?
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3 years ago
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What expression approximates the volume of O2 consumed, measure at STP, when 55 g of Al reacts completely with excess O2?2 Al(s)
Genrish500 [490]

Answer:

34.28 L ( 1.5*22.4 L)

Explanation:

Calculation of the moles of aluminum as:-

Mass = 55 g

Molar mass of aluminum = 26.981539 g/mol

The formula for the calculation of moles is shown below:

moles = \frac{Mass\ taken}{Molar\ mass}

Thus,

Moles= \frac{55\ g}{26.981539\ g/mol}

Moles= 2.0384\ mol

According to the reaction:-

4Al+3O_2\rightarrow 2Al_2O_3

4 moles of aluminum react with 3 moles of oxygen gas

1 mole of aluminum react with \frac{3}{4} moles of oxygen gas

2.0384 moles of aluminum react with \frac{3}{4}\times 2.0384 moles of oxygen gas

Moles of oxygen gas = 1.5288 moles

At STP,  

Pressure = 1 atm  

Temperature = 273.15 K

Using ideal gas equation as:

PV=nRT

where,

P is the pressure

V is the volume

n is the number of moles

T is the temperature

R is Gas constant having value = 0.0821 L.atm/K.mol

Applying the equation as:

1 atm × V = 1.5288 mol × 0.0821 L.atm/K.mol × 273.15 K

⇒V = 34.28 L ( 1.5*22.4 L)

7 0
3 years ago
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