How many moles are in 25.90 grams of NaCl

In a liquid, the energy required to increase the surface of the area by a unit amount is called :a.dipole-dipole force. b.viscos

Sedaia [141]

Answer:

D. Surface tension.

Explanation:

Surface tension is defined as the energy required to increase the surface area of a liquid by a unit amount.

The surface tension of a liquid results from an imbalance of intermolecular attractive forces, the cohesive forces between molecules:

A molecule in a liquid experiences cohesive forces with other molecules in all directions while molecules at the surface of a liquid experiences only net inward cohesive forces.

5 0

3 years ago

Water a combination of the elements hydrogen and oxygen, is an example of an

marin [14]

Answer:

Explanation:

Common Examples of the Law of Definite Proportions

Water, written as the chemical compound H20, is made up of atoms of hydrogen and oxygen. If one oxygen atom is combined with two hydrogen atoms, water is created.

3 0

3 years ago

The activation energy of an uncatalyzed reaction is 95kJ/mol. The addition of a catalyst lowers the activation energy to 55kJ/mo

notka56 [123]

Answer:

a) at 25°C the rate of reaction increases by a factor of 1,027*10^7

b) at 25°C the rate of reaction increases by a factor of 1,777*10^5

Explanation:

using the Arrhenius equation

k= ko*e^(-Ea/RT)

where

k= reaction rate

ko= collision factor

Ea= activation energy

R= ideal gas constant= 8.314 J/mol*K

T= absolute temperature

for the uncatalysed reaction

k1= ko*e^(-Ea1/RT)

for the catalysed reaction

k2= ko*e^(-Ea2/RT)

dividing both equations

k2/k1= e^(-(Ea2-Ea1)/RT)

a) at 25°C

k2/k1 = e^(-(55kJ/mol-95kJ/mol)/(8.314J/mol*K*298K)* (1000J/kJ ) ) = 1,027*10^7

therefore at 25°C , k2/k1 = 1,027*10^6

b) at 125°C

k2/k1 = e^(-(55kJ/mol-95kJ/mol)/(8.314J/mol*K*298K)* (1000J/kJ ) ) = 1,777*10^5

therefore at 125°C , k2/k1 = 1,777*10^5

Note:

when the catalysts is incorporated, the catalysed reaction and the uncatalysed one run in parallel and therefore the real reaction rate is

k real = k1 + k2 = k2 (1+k1/k2)

since k2>>k1 → 1+k1/k2 ≈ 1 and thus k real ≈ k2

6 0

3 years ago

Paradichlorobenzene, C6H4Cl2, is a component of mothballs. A solution of 2.00 g in 22.5 g of cyclohexane boils at 82.39 ∘C. The

Rina8888 [55]

Answer:

2.79 °C/m

Explanation:

When a nonvolatile solute is dissolved in a pure solvent, the boiling point of the solvent increases. This property is called ebullioscopy. The temperature change (ΔT) can be calculated by:

ΔT = Kb*W*i

Where Kb is the ebullioscopy constant for the solvent, W is the molality and i is the van't Hoff factor.

W = m1/(M1*m2)

Where m1 is the mass of the solute (in g), M1 is the molar mass of the solute, and m2 is the mass of the solvent (in kg).

The van't Hoff factor represents the dissociation of the elements. For an organic molecule, we can approximate i = 1. Thus:

m1 = 2.00 g

M1 = 147 g/mol

m2 = 0.0225 kg

W = 2/(147*0.0225)

W = 0.6047 mol/kg

(82.39 - 80.70) = Kb*0.6047*1

0.6047Kb = 1.69

Kb = 2.79 °C/m

4 0

3 years ago

What could you do to change the volume of a gas

Jet001 [13]

Solids and liquids have volumes thatdo not change easily. A gas, on the other hand, has a vol- ume thatchanges to match the volume of its container. The molecules in a gas are very far apart compared with the molecules in a solid or a liquid. The amount of space between the molecules in a gas can change easily.

5 0

3 years ago