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MissTica
2 years ago
13

5. What is the mole fraction of NaOH in an aqueous solution that contains 31.0 % NaOH by mass?

Chemistry
1 answer:
Liono4ka [1.6K]2 years ago
6 0

Answer:

16.8%      

Explanation:

31% NaOH    molar mass  40 gm

69% H2O      molar mass  18  gm

1000 gm would be  

 310 gm NaOH  or  310/40 = 7.75 moles

 690 gm of H2O or  690/18 = 38.333 moles

7.75 / (7.75 + 38.333) = .168   mole fraction

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STALIN [3.7K]

2000 BC and was found in tubes in Egyptian tombs dated from 1500BC

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4 0
3 years ago
Read 2 more answers
1. How much heat is required to melt 25.0 g of ice at 0°C?
tigry1 [53]

Answer: The heat required to melt 25.0 g of ice at 0^0C is 8350 Joules

Explanation:

Heat of Fusion tells us how much energy is needed to convert 1g of a solid to a liquid at the same temperature.

Q=m\times L

Q = Heat absorbed = ?  

m = mass of ice = 25.0 g

L = Latent heat of fusion of ice = 334 J/g

Putting in the values, we get:

Q=25.0g\times 334J/g=8350J

Thus heat required to melt 25.0 g of ice at 0^0C is 8350 Joules

8 0
3 years ago
Cindy made tea. She started with 300 grams of water at 20 degrees Celsius. She transferred 18,000 calories to the water. What wa
Serjik [45]

Answer:

T final = 80°C

Explanation:

  • Q = mCpΔT

∴ Q = 18000 cal

∴ m H2O = 300 g

∴ Cp H2O (15°C) = 0.99795 cal/g.K ≅ 1 cal/g.K

∴ T1 = 20°C = 293 K

∴ T2 = ?

⇒ 18000 cal = (300 g)(1 cal/g.K)(T2 - 293 K)

⇒ (18000 cal)/(300 cal/K) = T2 - 293 K

⇒ T2 = 293 K + 60 K

⇒ T2 = 353 K (80°C)

8 0
3 years ago
You were asked to determine the identity of an unknown liquid and can measure only one physical property. you heat the liquid an
Butoxors [25]
I did this before and i had got an A no it but its been along time tho
7 0
3 years ago
Given 4.80g of ammonium carbonate, find:
V125BC [204]

Answer:

1) 0.05 mol.

2) 0.1 mol.

3) 0.05 mol.

4) 0.4 mol.

5) 2.4 x 10²³ molecules.

Explanation:

<em>1) Number of moles of the compound:</em>

no. of moles of ammonium carbonate = mass/molar mass = (4.80 g)/(96.09 g/mol) = 0.05 mol.

<em>2) Number of moles of ammonium ions :</em>

  • Ammonium carbonate is dissociated according to the balanced equation:

<em>(NH₄)₂CO₃ → 2NH₄⁺ + CO₃²⁻.</em>

It is clear that every 1.0 mole of (NH₄)₂CO₃ is dissociated to produce 2.0 moles of NH₄⁺ ions and 1.0 mole of CO₃²⁻ ions.

<em>∴ The no. of moles of NH₄⁺ ions in 0.05 mol of (NH₄)₂CO₃ </em>= (2.0)(0.05 mol) =  <em>0.1 mol.</em>

<em>3) Number of moles of carbonate ions :</em>

  • Ammonium carbonate is dissociated according to the balanced equation:

<em>(NH₄)₂CO₃ → 2NH₄⁺ + CO₃²⁻.</em>

It is clear that every 1.0 mole of (NH₄)₂CO₃ is dissociated to produce 2.0 moles of NH₄⁺ ions and 1.0 mole of CO₃²⁻ ions.

∴ The no. of moles of CO₃²⁻ ions in 0.05 mol of (NH₄)₂CO₃ = (1.0)(0.05 mol) = 0.05 mol.

<em>4) Number of moles of hydrogen atoms:</em>

  • Every 1.0 mol of (NH₄)₂CO₃  contains:

2.0 moles of N atoms, 8.0 moles of H atoms, 1.0 mole of C atoms, and 3.0 moles of O atoms.

<em>∴ The no. of moles of H atoms in 0.05 mol of (NH₄)₂CO</em>₃ = (8.0)(0.05 mol) = <em>0.4 mol.</em>

<em>5) Number of hydrogen atoms:</em>

  • It is known that every mole of a molecule or element contains Avogadro's number (6.022 x 10²³) of molecules or atoms.

<u><em>Using cross multiplication:</em></u>

1.0 mole of H atoms contains → 6.022 x 10²³ atoms.

0.4 mole of H atoms contains → ??? atoms.

<em>∴ The no. of atoms in  0.4 mol of H atoms</em> = (6.022 x 10²³ molecules)(0.4 mole)/(1.0 mole) = <em>2.4 x 10²³ molecules.</em>

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3 years ago
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