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Tcecarenko [31]
3 years ago
7

Each student in a class placed a 2.00 g sample of a mixture of Cu and Al in a beaker and placed the beaker in a fume hood. The s

tudents slowly poured 15.0 mL of 15.8 M HNO3 into their beakers. The reaction between the copper in the mixture and the HNO3 is represented by the equation above. The students observed that a brown gas was released from the beakers and that the solutions turned blue, indicating the formation of Cu 2. The solutions were then diluted with distilled water to known volumes. The students determined that the reaction produced 0.010 mol of Cu(NO3)2. Based on the measurement, what was the percent of Cu by mass in the original 2.00 g sample of the mixture
Chemistry
1 answer:
Aleks [24]3 years ago
3 0

Answer:

Percentage mass of copper in the sample = 32%

Explanation:

Equation of the reaction producing Cu(NO₃) is given below:

Cu(s)+ 4HNO₃(aq) ---> Cu(NO₃)(aq) + 2NO₂(g) + 2H₂O(l)

From the equation of reaction, 1 mole of Cu(NO₃) is produced from 1 mole of copper. Therefore, 0.010 moles of Cu(NO₃) will be produced from 0.010 mole of copper.

Molar mass of copper = 64 g/mol

mass of copper = number of moles * molar mass

mass of copper = 0.01 mol * 64 g/mol = 0.64 g

Percentage by mass of copper in the 2.00 g sample = (0.64/2.00) * 100%

Percentage mass of copper in the sample = 32%

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Answer: conversion of ice to steam

Explanation: Endothermic process is one in which energy is absorbed by the system.

Conversion of ice to steam is change of solid phase to gaseous phase, thus energy is required to break the strong inter molecular forces of attraction in solids to convert it into gaseous phase.

Conversion of steam to ice, conversion of steam to water  and conversion of water to ice releases energy and are examples of exothermic processes.

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3 years ago
Ramelteon is a hypnotic agent used in the treatment of insomnia: Considering the labeled drawing above, which of the highlighted
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Answer:

1 and 2

Trigonal planar

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Trigonal Planar

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Explanation:

The highlighted atoms has a delocalized lone pair - 1 and 2

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and the other oxygen atom has geometry - Bent ( v- shape)

P.S - The correct question is -

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3 years ago
A certain system absorbs 350 joules of heat and has 230 joules of work done on it what is the value of
marysya [2.9K]
According to the law of conservation of mass, the amount of BARIUM present of the reactants is the same as the amount present in the products (the precipitate). 

(11.21 g BaSO4) / (233.4 g/mol BaSO4) = 0.0480 mol BaSO4 and original barium salt 

(10.0 g) / (0.0480 mol) = 208.3 g/mol 

So it must have been BaCl2, because the molar mass of Barium is 137 which leave 71 grams left. Since Barium is a +2 charge, it means the atom next to it must be twice. Chlorine mass is 35, which twice is 71
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8 0
3 years ago
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(4) Calculate the % of a compound that can be removed from liquid phase 1 by using ONE to FOUR extractions with a liquid phase 2
maksim [4K]

Answer:

One extraction: 50%

Two extractions: 75%

Three extractions: 87.5%

Four extractions: 93.75%

Explanation:

The following equation relates the fraction q of the compound left in volume V₁ of phase 1 that is extracted n times with volume V₂.

qⁿ = (V₁/(V₁ + KV₂))ⁿ

We also know that V₂ = 1/2(V₁) and K = 2, so these expressions can be substituted into the above equation:

qⁿ = (V₁/(V₁ + 2(1/2V₁))ⁿ = (V₁/(V₁ + V₁))ⁿ =  (V₁/(2V₁))ⁿ = (1/2)ⁿ

When n = 1, q = 1/2, so the fraction removed from phase 1 is also 1/2, or 50%.

When n = 2, q = (1/2)² = 1/4, so the fraction removed from phase 1 is (1 - 1/4) = 3/4 or 75%.

When n = 3, q = (1/2)³ = 1/8, so the fraction removed from phase 1 is (1 - 1/8) = 7/8 or 87.5%.

When n = 4, q = (1/2)⁴ = 1/16, so the fraction removed from phase 1 is (1 - 1/16) = 15/16 or 93.75%.

5 0
3 years ago
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