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2 years ago

What's the molality of a solution with 120 g of NaCl and 30 kg of water?

Chemistry

1 answer:

pogonyaev2 years ago

4 0

Answer: The correct option is A) 0.068 m

Explanation:

Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molarity:

$\text{Molality of solution}=\frac{\text{Given mass of solute}}{\text{Molar mass of solute}\times \text{Mass of solvent (in kg)}}$ .....(1)

We are given:

Given mass of NaCl = 120 g

Molar mass of NaCl = 58.45 g/mol

Mass of solvent = 30 kg

Putting values in equation 1, we get:

$\text{Molality of NaCl}=\frac{120}{58.44\times 30}\\\\\text{Molality of NaCl}=0.068m$

Hence, the correct option is A) 0.068 m

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In a molecule of calcium sulfide, calcium has two valence electron bonds, and a sulfur atom has six valence electrons. How many

mote1985 [20]

There are none

<h3>Further explanation</h3>

Given

a molecule of calcium sulfide

two valence electron of Calcium(Ca)

six valence electrons of Sulfur(S)

Required

number of lone pairs of electrons

Solution

Lewis structure shows the form of bonds that occur in the valence electrons of an element or compound

Valence electrons are electrons used in a chemical bond

To achieve stability, the element S needs 2 more electrons which are obtained from 2 electrons from the Ca element,

A lone pair electron means refers to an unshared pair of electrons(not bonding to the other atoms)

This condition usually occurs in covalent bonds

As we know, the bond between Ca, which is a group 2 (metal) with Sulfur in group 16, is an ionic bond because it occurs between metal and non-metal ions, so there is no sharing of electrons, but there is a release of electrons from Ca ions to S ions to form an octet. , so all the valence electrons in S are paired

7 0

3 years ago

Need help with 14 and 16 pls asap!! this is my friends test and im taking it tomorrow!!

marin [14]

Answer:

Q14: 17,140 g = 17.14 kg.

Q16: 504 J.

Explanation:

Q14:

To solve this problem, we can use the relation:

Q = m.c.ΔT,

where, Q is the amount of heat absorbed by ice (Q = 3600 x 10³ J).

m is the mass of the ice (m = ??? g).

c is the specific heat of the ice (c of ice = 2.1 J/g.°C).

ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = 100.0°C - 0.0°C = 100.0°C).

∵ Q = m.c.ΔT

∴ (3600 x 10³ J) = m.(2.1 J/g.°C).(100.0°C)

∴ m = (3600 x 10³ J)/(2.1 J/g.°C).(100.0°C) = 17,140 g = 17.14 kg.

Q16:

To solve this problem, we can use the relation:

Q = m.c.ΔT,

where, Q is the amount of heat absorbed by ice (Q = ??? J).

m is the mass of the ice (m = 12.0 g).

c is the specific heat of the ice (c of ice = 2.1 J/g.°C).

ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = 0.0°C - (-20.0°C) = 20.0°C).

∴ Q = m.c.ΔT = (12.0 g)(2.1 J/g.°C)(20.0°C) = 504 J.

6 0

3 years ago

1. How many hydrogen atoms are in 5 molecules of isopropyl alcohol, C3H7O

Gekata [30.6K]

1. c. 35
2. d. 1.26 x 10^24 molecules
3. d. 303.6 g

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3 years ago

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Metals have high melting and boiling points and are often shiny and silvery. Which of the blocks are metals?

DanielleElmas [232]

Answer:

S and p blocks elements are considered metals while d-block elements are considered transition metals.

Explanation:

s-block consist of lithium, sodium, potassium, rubidium, cesium and francium metals.

All are these called alkali metals.

These metals have one valance electron.

These metals are soft and having low density.

They easily lose their one valance electron and form cation with +1 charge.

They have low melting points.

P- block elements includes beryllium, magnesium, calcium, strontium, barium, radium metals.

They are called alkaline earth metals.

All are these have two valance electrons.

They easily lose their valance electrons and form cation with charge of +2.

These metals are also very soft.

They form salt with halogens.

They are also very reactive metals.

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3 years ago

What kind of matter is smoke?

Neporo4naja [7]

Answer : Colloid

Explanation : Any colloid which consist of a solid evenly dispersed in a gas phase can be called as smoke. So, if smoke has to be given a matter of substance then it is can be categorized as a Colloid present in gaseous phase. Smoke is a solid which contains minute particles of dust which is homogeneously dispersed in the air.

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3 years ago

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