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Ainat [17]
3 years ago
12

A certain substance X has a normal boiling point of 117.8°C and a molal boiling point elevation constant =Kb·0.63°C·kgmol−1. A s

olution is prepared by dissolving some urea NH22CO in 900.g of X. This solution boils at 118.3°C. Calculate the mass of urea that was dissolved. Round your answer to 1 significant digit.
Chemistry
1 answer:
OlgaM077 [116]3 years ago
5 0

Answer:

42.8 g was the mass of dissolved urea.

Explanation:

Boiling point elevation to solve this:

ΔT = Kb . m

where ΔT → Boiling T° of solution - Boiling T° of pure solvent

Let's replace the data given:

118.3°C - 117.8°C = 0.63°C/m . m

0.5°C / 0.63 m/°C = m → 0.793 mol/kg

Mass of solvent → 900 g → g to kg → 900 g . 1kg/1000 = 0.9 kg

Molality . kg = moles → 0.793 mol/kg . 0.9 kg = 0.714 mol

These are the moles of urea we used. Let's determine the mass dissolved.

0.714 mol . 60 g /1mol = 42.8 g

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Vika [28.1K]

Answer:

1 atom of carbon on the reactant side (CH₄ is methane, 1 carbon, 4 hydrogen).

1 atom of carbon on product side (Law of Conservation of energy proves this).

4 hydrogen on reactant side (CH₄ is methane, 1 carbon, 4 hydrogen).

4 hydrogen on product side (Again, the Law of Conservation of energy proves this)

4 oxygen atom on the reactant side (2O₂ means two diatomic molecules, or two oxygen molecules of 2 atoms each).

4 oxygen atoms on the product side (Law of Conservation of energy).

2 molecules of oxygen on the reactant side.

2 molecules of water on the product side

Yes, the chemical equation is balanced. The amount of atoms is the constant on both the reactant and product side.

A Ionic bond is chemical bond between two oppositely charged ions because of the transfer of valence electrons between them.

A covalent bond is a chemical bond in which two or more atoms share electrons between them. They can also form polar covalent bond or non-polar covalent bonds (Although that depends on the electronegativities of the atom).

The bond of a carbon dioxide molecule is covalent bond (Polar covalent bond if you've learned that yet)

Potassium Fluoride (KFl) form an ionic bond.

2Al₂O₃ --> 4Al + 3O₂

A reducing agent loses electrons while and oxidizing agent gains electrons.

In an endothermic reaction, the total bond energy in the reactants is greater than the bond energy of products so energy is absorbed by the reaction. (For an endothermic reaction, more energy needs to be absorbed than released).

8 0
3 years ago
What type of element is Hydrogen? Where do you see hydrogen present?
PSYCHO15rus [73]

/~\ The correct answer is:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

<em><u>Hydrogen is a chemical and is </u></em><em><u>found in the sun and most of the stars, </u></em><em><u>and the</u></em><em><u> planet Jupiter</u></em><em><u> is composed mostly of hydrogen. On Earth,</u></em><em><u> </u></em><em><u>hydrogen is found in the</u></em><em><u> greatest quantities as water.</u></em>

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I hope this helps! /~\

8 0
3 years ago
Zinc carbonate dissolves in water to the extent of 1.12 x 10-4 g/L at 25 C. Calculate the solubility product Ksp for ZnCO3 at 25
sashaice [31]

Answer:

Ksp= 7.98 × 10^-13

Explanation:

According to the question, we are to calculate the solubility constant (Ksp) of Zinc carbonate (ZnCO3) in a dissolved solution.

The equilibrium of the reaction is:

ZnCO3 (aq) ⇌ Zn2+ (aq) + CO32- (aq)

According to this; 1 mole of Zinc carbonate (ZnCO3) dissolves to give 1 mole of Zinc ion (Zn2+) and 1 mole of carbonate ion (CO32-).

This illustrates that:

(Zn2+) = 1.12 x 10-4 g/L

(CO32-) = 1.12 x 10-4 g/L

However, 1.12 x 10-4 g/L is the solubility in mass concentration of ZnCO3, we need to convert it to molar concentration in mol/L by dividing by the relative molar mass of ZnCO3.

To calculate the molar mass of ZnCO3, we say:

Zn (65.4) + C (12) + 03 (16×3)

= 65.4+12+48

= 125.4g/mol.

Hence, molar concentration= 1.12 x 10-4 g/L / 125.4 g/mol

= 8.93 × 10^-7 mol/L.

Therefore;

Zn2+) = 8.93 x 10-7 mol/L

(CO32-) = 8.93 x 10-7 mol/L

Ksp = [Zn2+] [CO32-]

Ksp = (8.93 x 10-7) × (8.93 x 10-7)

Ksp = 7.98 × 10^-13

3 0
3 years ago
An iron nail is made up of particles what is true about the particles
inn [45]

These particles are called as molecules and Can be further divided into smaller particles called atoms and these molecules are made up of same kind of atoms

7 0
3 years ago
Exactly 10.0 L of air -25°C is heated to 100.0°C. What is the new volume if the pressure is kept constant?
zepelin [54]

Answer: V2= 15.0403226 Liters

Explanation:

Use V1/T1=V2/T2

Make sure you change the degrees Celsius to Kelvin. (Kelvin = degrees Celsius +273)

10.0L / 248 K = V2/ 373 K

Cross multiply V1 and T2 and divide by T1

(10.0 L)( 373K)/ 248 K = V2

V2= 15.0403226 Liters (Kelvin cancels out)

4 0
3 years ago
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