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3 years ago

If a substance melts at 20oC, what is its freezing point?

Chemistry

1 answer:

shutvik [7]3 years ago

4 0

Answer:

It is difficult, if not impossible, to heat a solid above its melting point because the heat that ... in a solid are packed in a regular structure that is characteristic of that particular substance.

<h3>#carryONlearning </h3>

You might be interested in

Calculate the osmotic pressure of a solution containing 24.6g of glycerin in 250ml of solution at 298K

gavmur [86]

The formula to calculate osmotic pressure is
Osmotic Pressure = M R T
M = Molarity
R = Ideal Gas Constant
T = Temperature in Kelvin

So,
24.6/.2254kg=109.139g /kg >>>>> Molarity
109.139 x mols/92 g = 1.186 mols kg^-1
1.186 x 0.08134 x 298 K = 28.755 atm
<span>1.06852 x 0.08134 x 298K= 26.5 atm

The answer is 26.5</span>

6 0

3 years ago

A chemist measures the enthalpy change ?H during the following reaction: Fe (s) + 2HCl (g) ? FeCl2 (s) + H2 (g) =?H?157.kJ Use t

erik [133]

Correct Question:

A chemist measures the enthalpy change ΔH during the following reaction: Fe(s) + 2HCl(g)-->FeCl2(s) + H2 ΔH=-157.0 kJ. Use this information to complete the table below. Round each of your answers to the nearest kJ/mol

Answer:

-314 kJ

+628 kJ

+157 kJ

Explanation:

The enthalpy change of a reaction measures the amount of heat that is lost or gained by it. If ΔH >0 the heat is gained, and the reaction is called endothermic, if ΔH<0, the heat is lost, and the reaction is called exothermic.

If the reaction is inverted, the value of ΔH is inverted too (the opposite endothermic reaction is exothermic), and if the reaction is multiplied by a constant, ΔH will be multiplied by it too.

1) 2Fe(s) + 4HCl --> 2FeCl2(s) + 2H2(g)

This reaction is the product of the given reaction by 2, so

ΔH = 2*(-157) = -314 kJ

2) 4FeCl2(s) + 4H2(g) --> 4Fe(s) + 8HCl(g)

This reaction is the inverted reaction given multiplied by 4, so

ΔH = 4*(157) = +628 kJ

3) FeCl2(s) + H2(g) --> Fe(s) + 2HCl

This reaction is the inverted reaction given, so

ΔH = +157 kJ

4 0

3 years ago

Substance X has a fixed volume, and the attraction between its particles is strong. Substance Y has widely spread out particles

ycow [4]

Answer: Option (d) is the correct answer.

Explanation:

In solids, molecules are held together by strong intermolecular forces of attraction. As a result, they are unable to move from their initial position and can only vibrate at their mean position.

Hence, a solid has definite shape and volume. Solids cannot be compressed.

Whereas in plasma, molecules are hot ionized which include positively charged ions and negatively charged electrons. They collide much more rapidly with each other and are widely spreaded out.

Therefore, they occupy the volume of container in which they are placed. Plasma can be compressed.

Thus, we can conclude that substance X is a solid and substance Y is a plasma.

6 0

2 years ago

Read 2 more answers

The specific heat for liquid ethanol is 2.46 J/(g•°C). When 210 g of ethanol is cooled from

avanturin [10]

Answer:

a) heat it from 23.0 to 78.3

q = (50.0 g) (55.3 °C) (2.46 J/g·°C) =

b) boil it at 78.3

(39.3 kJ/mol) (50.0 g / 46.0684 g/mol) =

c) sum up the answers from the two calculations above. Be sure to change the J from the first calc into kJ

Explanation:

3 0

3 years ago

How many excess electrons must be added to an isolated spherical conductor 41.0 cmcm in diameter to produce an electric field of

alina1380 [7]

Answer:

3.65 x 10¹⁰ electrons

Explanation:

we'll apply the following equation for electric field of a point charge on a spherical conductor

$E = k \frac{q}{r^{2} }$

where E is the electric field

k is a constant of the value 8.99 x 10⁹ Nm²/C²

r is the radius of the spherical conductor

q is the total charge in the sphere

Given diameter d =41.0cm, radius r = 20.5cm = 0.205m (convert cm to m)

Electrical field E = 1250 N/C

we are asked to determine how many excess electrons must be added to the surface of the sphere to produce this electric field

$E = k \frac{q}{r^{2} }$

q = <u>E x r²</u>

q = <u>1250 N/C x 0.205m</u>²

8.99 x 10⁹ Nm²/C²

q = 5.84 x 10⁻⁹ C

this is the total charge in the sphere

To determine the number of electrons, we can divide the charge q by the charge on an electron e (1.6 x 10⁻¹⁹C)

$n = \frac{q}{e}$

n = <u>5.84 x 10⁻⁹ C </u>

1.6 x 10⁻¹⁹C

n = 3.65 x 10¹⁰ electrons

Therefore, to apply an electric field of magnitude 1250 N/C, the isolated spherical conductor must contain 3.65 x 10¹⁰ electrons

3 0

3 years ago