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DanielleElmas [232]
1 year ago
9

(Yield Problem)

Chemistry
1 answer:
alex41 [277]1 year ago
5 0

Answer:

Percent Yield Fe  =  82.5%

Explanation:

The actual yield is the value produced after an experiment is conducted. The theoretical yield is the value calculated using the balanced chemical equation and atomic/molar masses.

To find the percent yield of iron (Fe), you need to (1) convert grams Al to moles Al (via atomic mass), then (2) convert moles Al to moles Fe (via mole-to-mole ratio from equation coefficients), then (3) convert moles Fe to grams Fe (via atomic mass), and then (4) calculate the percent yield. It is important to arrange the ratios in a way that allows for the cancellation of units. The final answer should have 3 sig figs to reflect the sig figs of the given values.

Atomic Mass (Mg): 24.305 g/mol

Atomic Mass (Fe): 55.845 g/mol

3 Mg + 2 FeCl₃ -----> 2 Fe + 3 MgCl₂

20.5 g Mg           1 mole              2 moles Fe            55.845 g
-----------------  x  -----------------  x  ----------------------  x  -----------------  =  
                           24.305 g           3 moles Mg             1 mole

=  31.4 g Fe

                                     Actual Yield
Percent Yield  =  ----------------------------------  x  100%
                                 Theoretical Yield

                               25.9 g Fe
Percent Yield  =  --------------------  x  100%
                               31.4 g Fe

Percent Yield  =  82.5%

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How many moles of sodium carbonate are contained by 57.3g of sodium carbonate
Lady_Fox [76]

Answer:

\boxed {\boxed {\sf 0.541 \  mol \ Na_2CO_3}}

Explanation:

We are asked to find how many moles of sodium carbonate are in 57.3 grams of the substance.

Carbonate is CO₃ and has an oxidation number of -2. Sodium is Na and has an oxidation number of +1. There must be 2 moles of sodium so the charge of the sodium balances the charge of the carbonate. The formula is Na₂CO₃.

We will convert grams to moles using the molar mass or the mass of 1 mole of a substance. They are found on the Periodic Table as the atomic masses, but the units are grams per mole instead of atomic mass units. Look up the molar masses of the individual elements.

  • Na:  22.9897693 g/mol
  • C: 12.011 g/mol
  • O: 15.999 g/mol

Remember the formula contains subscripts. There are multiple moles of some elements in 1 mole of the compound. We multiply the element's molar mass by the subscript after it, then add everything together.

  • Na₂ = 22.9897693 * 2= 45.9795386 g/mol
  • O₃ = 15.999 * 3= 47.997 g/mol
  • Na₂CO₃= 45.9795386 + 12.011 + 47.997 =105.9875386 g/mol

We will convert using dimensional analysis. Set up a ratio using the molar mass.

\frac {105.9875386  \ g \ Na_2CO_3}{1 \ mol \ Na_2CO_3}

We are converting 57.3 grams to moles, so we multiply by this value.

57.3 \ g \ Na_2CO_3} *\frac {105.9875386  \ g \ Na_2CO_3}{1 \ mol \ Na_2CO_3}

Flip the ratio so the units of grams of sodium carbonate cancel.

57.3 \ g \ Na_2CO_3} *\frac {1 \ mol \ Na_2CO_3}{105.9875386  \ g \ Na_2CO_3}

57.3 } *\frac {1 \ mol \ Na_2CO_3}{105.9875386 }

\frac {57.3 }{105.9875386 } \ mol \ Na_2CO_3

0.5406295944 \ mol \ Na_2CO_3

The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we found that is the thousandth place. The 6 in the ten-thousandth place to the right tells us to round the 0 up to a 1.

0.541 \  mol \ Na_2CO_3

There are approximately <u>0.541 moles of sodium carbonate</u> in 57.3 grams.

6 0
2 years ago
Why is the water cycle called a cycle and not a system?
alexira [117]
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5 0
3 years ago
How old is a bone if it now .3125 of C-14 when it originally had 80.0g of C-14
Taya2010 [7]
<h3>Answer:</h3>

42960 years

<h3>Explanation:</h3>

<u>We are given;</u>

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  • Original mass of C-14 on the bone is 80.0 g
  • Half life of C-14 is 5370 years

We are required to determine the age of the bone;

  • Using the formula;
  • Remaining mass = Original mass × 0.5^n , where n is the number of half lives.

Therefore;

0.3125 g = 80.0 g × 0.5^n

3.90625 × 10^-3 = 0.5^n

  • Introducing logarithm on both sides;

log 3.90625 × 10^-3 = n log 0.5

Solving for n

n = log 3.90625 × 10^-3 ÷ log 0.5

   = 8

  • Therefore, the number of half lives is 8
  • But, 1 half life is 5370 years
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Age of the rock = 5370 years × 8

                          = 42960 years

Thus, the bone is 42960 years old

7 0
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Answer:

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f = v / λ

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