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LenaWriter [7]
3 years ago
9

A student obtained 1.69 g of pure caffeine following recrystallization from a crude sample, which originally weighed 2.51 g. Wha

t is the percent recovery of pure caffeine from crude?
Chemistry
1 answer:
Savatey [412]3 years ago
5 0

Answer:

The recovery of pure caffeine is 67.3% of the original, crude sample.

Explanation:

Step 1: Data given

Mass of pure caffeine = 1.69 grams

Original mass of sample = 2.51 grams

Step 2: What is the percent recovery of pure caffeine from crude?

Percentage = (mass of recovery / original mass) *100%

Percentage = (1.69 grams/2.51 grams) *100%

Percentage = 67.3 %

The recovery of pure caffeine is 67.3% of the original, crude sample.

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Both diamond and graphite (i.e. pencil lead) consist of carbon atoms. They are only different in their crystalline structures. O
prisoha [69]

Answer:

Moles of carbon atoms  = 3.33  ×  10^{-6} mol

No. of atoms of C in Diamond  = 2.007 ×   10^{28} atom

Atoms of graphite = 6.27 × 10^{23} Atoms

Explanation:

given data

Cost of 0.2g of diamond = $5000

Cost of 25 g of graphite = $ 2

solution

we know cost of 0.2g of diamond is $ 5000 so that for 1$

if buy 1$ = \frac{0.20}{5000}

1$ = 4.0 × 10^{-5} g Carbon

and Moles of carbon atoms  is express as

Moles of carbon atoms = Given mass of Carbon ÷ atomic mass of C      .........1

Moles of carbon atoms  = 4.0  ×  10^{-5}    g/ 2.0g

Moles of carbon atoms  = 3.33  ×  10^{-6} mol

and

No. of atoms of C in Diamond = No. of moles × Avogadro NO    ..............2

No. of atoms of C in Diamond  = 3.33 ×   10^{-6} mol × 6.022 ×   10^{28}

No. of atoms of C in Diamond  = 2.007 ×   10^{28} atom

Graphite

and wew have given Cost of 25 g of graphite is $2 so for but 1$ we get

for buy $1 = 25÷2  = 12.5 g Of graphite

Moles of graphite = 12.5÷12 = 1.04 mol

Atoms of graphite = 1.04 × 6.022 × 1023

Atoms of graphite = 6.27 × 10^{23} Atoms

6 0
3 years ago
When the first American astronauts were planning to walk on the Moon, they knew that the gravity on the Moon was less than the g
Anon25 [30]

Answer:

Their weight.

Explanation:

Weight is the measurement of gravity pushing you down, so with less gravity there would be less weight.

3 0
3 years ago
Which of the following free-body diagrams is a balanced force?
sleet_krkn [62]

Answer:

2

Explanation:

#1 is incorrect as there is no upward force that would balance the 5 N downward force

#3 is incorrect 2 is less than 5 = net force downward of 3 N

#4 is incorrect 5 is greater than three = 2 N net force going to the left and 2N going up

4 0
3 years ago
according to the diagram, what three quantities can you calculate if you know the number of moles of a compound
Tems11 [23]

The number of moles of a substance can be used to calculate its mass, the number of atoms present in the compound as well as the number of moles of individual atoms/ions in the compound.

The number of moles of a compound or ion is defined as the ratio of its mass to its molar mass. The number of moles of a substance is very important when performing stoichiometric calculations.

If you have the number of moles of  a substance you can find;

  • The mass of the substance
  • The number of atoms or ions in the substance
  • The number of moles of individual atoms/ ions in the substance.

Learn more: brainly.com/question/865531

4 0
2 years ago
What is the theoretical yield of aluminum oxide if 1.40 mol of aluminum metal is exposed to 1.35 mol of oxygen?
vladimir2022 [97]

Answer:

71.372 g or 0.7 moles

Explanation:

We are given;

  • Moles of Aluminium is 1.40 mol
  • Moles of Oxygen 1.35 mol

We are required to determine the theoretical yield of Aluminium oxide

The equation for the reaction between Aluminium and Oxygen is given by;

4Al(s) + 3O₂(g) → 2Al₂O₃(s)

From the equation 4 moles Al reacts with 3 moles of oxygen to yield 2 moles of Aluminium oxide.

Therefore;

1.4 moles of Al will require 1.05 moles (1.4 × 3/4) of oxygen

1.35 moles of Oxygen will require 1.8 moles (1.35 × 4/3) of Aluminium

Therefore, Aluminium is the rate limiting reagent in the reaction while Oxygen is the excess reactant.

4 moles of aluminium reacts to generate 2 moles aluminium oxide.

Therefore;

Mole ratio Al : Al₂O₃ is 4 : 2

Thus;

Moles of Al₂O₃ = Moles of Al × 0.5

                         = 1.4 moles × 0.5

                         = 0.7 moles

But; 1 mole of Al₂O₃ = 101.96 g/mol

Thus;

Theoretical mass of Al₂O₃ = 0.7 moles × 101.96 g/mol

                                            = 71.372 g

7 0
3 years ago
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