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3 years ago

Which of the following is an example of a chemical change?

1 answer:

6 0

The best answer is the first option. A bike rusting is an example of a chemical change since rusting is a chemical reaction. New substances are formed from this reaction. On the other hand, other choices given are just physical changes because only the shape or the physical form of the substances are being changed.

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When octane (C8H18) is burned in the presence of oxygen, the yield of products (carbon dioxide and water) is 87%. What mass of c

ahrayia [7]

Answer:

14.5g of CO₂ are produced

Explanation:

The reaction of octane with oxygen is:

C₈H₁₈ + 25/2O₂ → 8CO₂ + 9H₂O

Where 1 mole of octane (Molar mass: 114.23g/mol) reacts with 25/2 moles of O₂ (Molar mass 32g/mol) to produce 8 moles of CO₂ and 9 moles of water.

When 21.0 g of octane is burned with 19.0 g of oxygen gas you need to find limiting reactant to find how many moles of products are formed:

Octane: 21.0g ₓ (1mol / 114.23g) = 0.184 moles octane

Oxygen: 19.0g ₓ (1 mol / 32g) = 0.594 moles oxygen

For a complete reaction of 0.184 moles of octane you will need:

0.184 moles C₈H₁₈ ₓ (25/2 moles O₂ / 1 mole C₈H₁₈) = 2.3 moles of oxygen

As you have just 0.594 moles of oxygen, Oxygen is limiting reactant.

Based on chemical equation, 25/2 of O₂ produce 8 moles of CO₂, that means theoretical yield of CO₂ with 0.594 moles of O₂ is:

0.594 moles O₂ ₓ (8 moles CO₂ / 25/2 moles O₂) = 0.380 moles of CO₂

But, as yield of products is 87%, moles produced of CO₂ are:

0.380 moles of CO₂ ₓ 87% = 0.331 moles CO₂ are produced.

As molar mass of CO₂ is 44g/mol, mass of CO₂ in 0.331 moles is:

0.331 moles CO₂ ₓ (44g / mol) =

<h3>14.5g of CO₂ are produced</h3>

6 0

3 years ago

Calculate the molarity of an hcl solution if a 10.00 ml sample requires 25.24 ml of a 1.600 m naoh solution to be neutralized.

AlladinOne [14]

Answer:

The molarity of the HCl solution should be 4.04 M

Explanation:

Step 1: Data given

volume of HCl solution = 10.00 mL = 0.01 L

volume of a 1.6 M NaOH solution = 25.24 mL = 0.02524 L

Step 2: The balanced equation

HCl + NaOH → NaCL + H2O

Step 3: Calculate molarity of HCl

n1*C1*V1 = n2*C2*V2

Since the mole ratio for HCl and NaOH is 1:1 we can just write:

C1*V1 =C2*V2

⇒ with C1 : the molarity of HCl = TO BE DETERMINED

⇒ with V1 = the volume og HCl = 10 mL = 0.01 L

⇒ with C2 = The molarity of NaOH = 1.6 M

⇒ with V2 = volume of NaOH = 25.24 mL = 0.02524 L

C1 * 0.01 = 1.6 * 0.02524

C1 = (1.6*0.02524)/0.01

C1 = 4.04M

The molarity of the HCl solution should be 4.04 M

6 0

3 years ago

What is the best example of an experimental scientific investigation?

ivolga24 [154]

Scientific investigation: The process in which scientist solve the question by using different systematic approach. It can be initiated in different ways.

Experimental Scientific investigation: The investigation in which scientist answer the question on the basis of experimental results. Experimental investigation includes both dependent and independent variables, and only one variable is tested at a time is possible.

The best example of an experimental scientific investigation is: when we placed a whole apple and apple slice under sun, and noted down how many days it will take to rot in order to compare the break down of apple slice and whole apple.

Thus, option (B) is the correct answer.

7 0

3 years ago

HELP PLEASE I BEG OF YOU

Vitek1552 [10]

Answer:

37.7%

Explanation:

58% of 65 is 37.7%

7 0

2 years ago

Scenario Two:

galben [10]

Answer:

jo mom cause why not

Explanation:

7 0

3 years ago