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boyakko [2]
2 years ago
6

How many molecules of water of water are in a 821.3 g sample

Chemistry
1 answer:
svetlana [45]2 years ago
6 0

Answer: 2.744 x 1025 molecules

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Ethanol, C2H6O, is most often blended with gasoline - usually as a 10 percent mix - to create a fuel called gasohol. Ethanol is
weeeeeb [17]

Answer:

This means 463 grams of ethanol would provide less amount of energy

Explanation:

Step 1: Data given

Heat of combustion of ethanol = 326.7 kcal/mol

The heat of combustion of octane =  1.308*10³ kcal/mol

Mass of octane = 463 grams

Molar mass octane = 114.23 g/mol

Molar mass ethanol = 46.07 g/mol

Step 2: Calculate moles octane

Moles octane = mass octane / molar mass octane

Moles octane = 463 grams / 114.23 g/mol

Moles octane = 4.05 moles

Step 3: Calculate energy of combustion of 4.05 moles octane

Combustion of 1 mol octane gives us: 1.308 * 10³ kcal/mol

Combustion of 4.05 moles octane gives us 4.05 * 1.308 * 10³ kcal/mol = <u>5.30 * 10³ kcal</u>

This means the combustion reaction of 463 grams of octane gives us 5.30 * 10³ kcal

Step 4:

Heat of combustion of ethanol = 326.7 kcal/mol

OR in words: combustion of 1 mol ethanol gives us 326.7 kcal energy

Moles ethanol = 463 grams / 46.07 g/mol

Moles ethanol = 10.05 moles

Since combustion of 1 mol ethanol gives us 326.7 kcal

10.05 moles ethanol will give us = 10.05 * 326.7 = 3283.3 kcal = <u>3.28 * 10³ kcal</u>

<u />

5.30 * 10³ kcal > 3.28 * 10³ kcal

This means 463 grams of ethanol would provide less amount of energy

3 0
3 years ago
Which equation best represents the dissociation of water molecules into hydrogen ions and hydroxide ions?
Nikitich [7]

Answer is: H₂O → H⁺ + OH⁻.

Water dissociates (autoionization) to form hydrogen ions (H⁺) and hydroxide (OH⁻) ions. The protons (H⁺) hydrate as hydroxonium ions( H₃O⁺).

The Kw (the ionic product for water) at 25°C is 1·10⁻¹⁴ mol²/dm⁶ or 1·10⁻¹⁴ M². Concentration of hydrogen ions and hydroxide ions in pure water are the same.

7 0
3 years ago
Read 2 more answers
How does water change when it is frozen?
vredina [299]

Answer:

the molecules of water contracts when it is frozen

7 0
2 years ago
List three differences between the earth 240 million years ago and the present earth.
raketka [301]
Dinosaurs, cavemen, sabertooth tiger
4 0
3 years ago
The state of matter in which a material has a definite shape and a definite volume is the _____ state.
Scilla [17]

Answer:

solid

Explanation:

in the solid state the material will has a fixed shape and volume whatever the container that contains it

where in liquid the shape will be different depending on the container

and in gas state the shape and volume are not definite

3 0
2 years ago
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