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Tamiku [17]
3 years ago
9

A person uses 770 kcal on a long hike. Calculate the energy used for the hike in each of the following energy units.

Chemistry
1 answer:
Pavlova-9 [17]3 years ago
5 0

Explanation:

1 Cal of energy is equivalent to 4.184 Joules.

A.

770Cal of energy = 3221.680 joules

Therefore, 780kCal of energy = 3221680 Joules.

B.

3200000 Joules (in 2 s.f).

C.

I000 joules = 1 kJoule

3221680 joules = 3221.689 kJoules.

D.

3200 kJ (in 2 s.f).

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Ions. Im 99.9% sure haha. 
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3 years ago
A sample of solid sodium hydroxide, weighing 13.20 grams is dissolved in deionized water to make a solution. What volume in mL o
Andreas93 [3]
<h3>Answer:</h3>

2.809 L of H₂SO₄

<h3>Explanation:</h3>

Concept tested: Moles and Molarity

In this case we are give;

Mass of solid sodium hydroxide as 13.20 g

Molarity of H₂SO₄ as 0.235 M

We are required to determine the volume of H₂SO₄ required

<h3>First: We need to write the balanced equation for the reaction.</h3>
  • The reaction between NaOH and H₂SO₄ is a neutralization reaction.
  • The balanced equation for the reaction is;

2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

<h3>Second: We calculate the umber of moles of NaOH used </h3>
  • Number of moles = Mass ÷ Molar mass
  • Molar mass of NaOH is 40.0 g/mol
  • Therefore;

Moles of NaOH = 13.20 g ÷ 40.0 g/mol

                          = 0.33 moles

<h3>Third: Determine the number of moles of the acid, H₂SO₄</h3>
  • From the equation, 2 moles of NaOH reacts with 1 mole of H₂SO₄
  • Therefore, the mole ratio of NaOH: H₂SO₄ is 2 : 1.
  • Thus, Moles of H₂SO₄ = moles of NaOH × 2

                                    = 0.33 moles × 2

                                   = 0.66 moles of H₂SO₄

<h3>Fourth: Determine the Volume of the acid, H₂SO₄ used</h3>
  • When given the molarity of an acid and the number of moles we can calculate the volume of the acid.
  • That is; Volume = Number of moles ÷ Molarity

In this case;

Volume of the acid = 0.66 moles ÷ 0.235 M

                                = 2.809 L

Therefore, the volume of the acid required to neutralize the base,NaOH is 2.809 L.

7 0
4 years ago
When combining acids and water, water should always be added to the acid. True or False?
scoundrel [369]

Answer:

False

Explanation:

Always add acid to the water, it dilutes the acid the other way around.

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Outline two methods used by designers to assemble packages​
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Answer:

Product packaging design refers to the production of a product's exterior. Develop an organization. All these specifics allow one to consider what the sealed substance is about how to use it, who can use it, and maybe, What do you sell? For your product, there are several different packaging forms available.

Explanation:

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A: part 1 consumers, part 2 the sun

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