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Vinvika [58]
3 years ago
5

(HELP FAST)Which of the following always changes when a substance undergoes a chemical change?

Chemistry
2 answers:
Lera25 [3.4K]3 years ago
7 0
I’m pretty sure it’s a
GrogVix [38]3 years ago
3 0
A- the change of matter
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Consider the reaction 2 al + Fe2O3 to 2Fe + Al2O3. If 60.0g of Al is reacted with excess Fe2O3, determine the amount (in moles)
olganol [36]

 The  amount  of  Al2O3  in moles=  1.11 moles    while in  grams   = 113.22 grams


    <em><u>calculation</u></em>

     2 Al  + Fe2O3 → 2Fe  + Al2O3

    step  1: find the moles of Al  by  use of <u><em>moles= mass/molar  mass  </em></u>formula

    =  60.0/27= 2.22  moles


    Step 2: use the mole ratio to determine the  moles of Al2O3.

 The  mole ratio  of Al : Al2O3 is  2: 1 therefore the moles of Al2O3= 2.22/2=1.11  moles


Step 3:    finds the mass  of  Al2O3  by us of  <u><em>mass= moles x molar mass</em></u><em> </em>formula.

The molar  mass of Al2O3  =  (2x27)  +( 16 x3) = 102  g/mol

mass is therefore=  102  g/mol  x 1.11= 113.22 grams


             

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3 years ago
How do newtons 3 laws relate ​
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I need help with B and C
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3 years ago
An excess of oxygen reacts with 451.4 g of lead, forming 374.7 g of lead(II) oxide. Calculate the percent yield of the reaction.
Stels [109]

Answer: The percent yield of the reaction is 77.0 %

Explanation:

2Pb+O_2\rightarrow 2PbO

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

\text{Number of moles of lead}=\frac{451.4g}{207.2g/mol}=2.18moles

\text{Number of moles of lead oxide}=\frac{374.7g}{223.2g/mol}=1.68moles

According to stoichiometry:

2 moles of Pb produces = 2 moles of PbO_2

2.18 moles of Pb is produced by=\frac{2}{2}\times 2.18=2.18moles of PbO_2

Mass of PbO_2 =moles\times {\text {Molar mass}}=2.18\times 223.2g/mol=486.6

percent yield =\frac{374.7g}{486.6g}\times 100=77.0\%

3 0
3 years ago
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