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RoseWind [281]
3 years ago
6

What is the correct answer to the following expression: (72.61 - 68.59) x 18.76? Be sure to express your answer using the correc

t number of significant figures.
Chemistry
1 answer:
ZanzabumX [31]3 years ago
6 0
To answer this expression we should follow the mathematical rule. The mathematical rule that we will follow is called BODMAS short for brackets, powers, divide, multiply, add, subtract. So, we will first solve the one in the brackets which is <span>(72.61 - 68.59) is equal to 4.02 then we will multiply this to 18.76 and the answer is 75.4152.</span>
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Please help I need the answer now. Write a balanced equation for combustion of pentane in plenty supply of air and in limited su
Ratling [72]

Pentane burns in plenty of air: CO₂ and H₂O is produced.

C₅H₁₂ + 8 O₂ → 5 CO₂ + 6 H₂O

Pentane burns in limited amount of air: CO or even C is produced along with H₂O.

2 C₅H₁₂ + 11 O₂ → 10 CO + 12 H₂O

<h3>Explanation</h3>

Pentane is a hydrocarbon. There are five carbon atoms in each of its molecule. Its molecular formula will be C₅H₁₂.

Hydrocarbon fuels burn to produce CO₂ when there's plenty of air.

? C₅H₁₂ + ? O₂ → ? CO₂ + ? H₂O

  • Among all species in this reaction, C₅H₁₂ has the largest number of atoms per molecule. Assume that the coefficient of C₅H₁₂ is one.

<em>1</em> C₅H₁₂ + ? O₂ → ? CO₂ + ? H₂O

  • C₅H₁₂ is the only <em>reactant</em> that contains C atoms. There are 5 C atoms in a C₅H₁₂ molecule. There should be the same number of C atoms in the products.
  • CO₂ is the only <em>product</em> that contains C atoms. There are one C atom in each CO₂ molecule. 5 C atoms correspond to 5 CO₂ molecules.

<em>1 </em>C₅H₁₂ + ? O₂ → <em>5</em> CO₂ + ? H₂O

  • Similarly, C₅H₁₂ is the only <em>reactant</em> that contains H atoms. H₂O is the only <em>product</em> that contains H atoms. There are 12 H atoms in one C₅H₁₂ molecule, which corresponds to 6 H₂O molecules.

<em>1</em> C₅H₁₂ + ? O₂ → <em>5</em> CO₂ + <em>6</em> H₂O

  • Both CO₂ and H₂O are <em>products</em> that contains O atoms. There are 5 × 2 + 6 × 1 = 16 O atoms in total in 5 CO₂ molecules and 6 H₂O molecules. The 16 O atoms on the <em>product</em> side corresponds to 8 O₂ molecules on the reactant side.

<em>1</em> C₅H₁₂ + <em>8</em> O₂ → <em>5</em> CO₂ + <em>6</em> H₂O

1 C₅H₁₂ + 8 O₂ → 5 CO₂ + 6 H₂O

  • All coefficients shall be whole numbers. If there's any fraction in this equation, multiply both sides by the least common multiple of their denominators.

Hydrocarbon fuels burn to produce H₂O and CO when there's a limited supply of air. C (soot) might also be produced. Assuming that only CO is produced. Try to balance the equation using the same method.

1 C₅H₁₂ + 11/2 O₂ → 5 CO + 6 H₂O

2 C₅H₁₂ + 11 O₂ → 10 CO + 12 H₂O

Less O₂ is consumed for each mole of C₅H₁₂.

Consider: What would be the balanced equation when only C is produced?

<h3>Reference</h3>

"Products and effects of combustion", <em>GCSE Chemistry (Single Science)</em>, BBC Bitesize.

5 0
3 years ago
2. What are the different areas of an electron cloud called?
Ghella [55]
Shells (electrons) - located in the cloud
nucleus- located in the center
energy level - is determined by the electron count ( level 1 - 2 electrons
level 2 - 8 electrons
level 3- 18 electrons)

5 0
3 years ago
The mass and volume of each box is given in the chart below. Calculate the density of each box. Density = Mass/ volume which box
stira [4]

Box C will have the greatest density.

All boxes have the same volume.

Explanation:

We calculate the density using the following formula:

density = mass / volume

density of Box A = 10 g / 20 cm³ = 0.5 g/cm³

density of Box B = 30 g / 20 cm³ = 1.5 g/cm³

density of Box C = 170 g / 20 cm³ = 8.5 g/cm³

Box C will have the greatest density.

All boxes have the same volume.

Learn more about:

density

brainly.com/question/952755

#learnwithBrainly

7 0
3 years ago
How many moles of carbon dioxide gas can be produced when 7.94 moles of benzene (C6H6) react with excess oxygen? Be sure to show
Sliva [168]
The balanced equation is 

<span>2 C6H6 +15 O2 = 12 CO2 + 6 H2O </span>

<span>the ratio between C6H6 and CO2 is 2 : 12 </span>

<span>moles CO2 produced = 7.94 x 12 / 2 =47.6</span>
6 0
3 years ago
Parents should avoid sharing their own mistakes with children. True/false
Vesna [10]
Parents SHOULDN'T avoid sharing their own mistakes with children.
6 0
3 years ago
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