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2 years ago

What happens to ice as it melts energy

Chemistry

1 answer:

KonstantinChe [14]2 years ago

5 0

Answer:

Energy is added (postive enthalpy)

Explanation:

Ice melting means solid turns into liquid. Solid is more stable than liquid thus you must put in energy to weaken the forces of solid and turn it into liquid. Thus, you must put in energy to melt ice. This makes the enthalpy of the system to be positive.

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if a gas sample has a pressure of 761 mmhg at 0.00°c by how much does the temperature have to decrease to lower the pressure to

Nady [450]

<h3>Answer:</h3>

272.43 K or -0.718°C

<h3>Explanation:</h3>

We are given;

The initial pressure,P1 as 761 mmHg

Initial temperature, T1 as 0.00°C which is equivalent to 273.15 K

Final pressure as 759 mmHg

We are required to calculate the final temperature;

According to pressure law, the pressure of a gas and absolute temperature are directly proportional at constant volume.

That is; Pα T

Therefore, at varying pressure and temperature,

$\frac{P1}{T1}=\frac{P2}{T2}$

To get final temperature;

$T2=\frac{P2T1}{P1}$

$T2=\frac{(759 mmHg)(273.15K)}{761 mmHg}$

$T2=272.43K$

Therefore, the final temperature will be 272.43 K or -0.718°C

6 0

3 years ago

20 ml of a solution of sucrose contains 850 mg of sucrose. What is the weight/volume percentage concentration of this solution i

MissTica

<h3>Answer: 4.25 g/ml %</h3>

Explanation:

weight/volume percentage concentration = (mass in g ÷ volume) × 100

= (0.850 g ÷ 20 ml) × 100

= 4.25 g/ml %

∴ the weight/volume percentage concentration of the sucrose solution is 4.25 g/ml %.

7 0

3 years ago

In each row check off the boxes that apply to the highlighted reactant. reaction The highlighted reactant acts as a... (check al

tekilochka [14]

The given question is incomplete. The complete question is :

In each row check off the boxes that apply to the underlined reactant. The underlined reactant acts as a... (check all that apply)

1. $HCH_3CO_2(aq)+NH_3(aq)\rightarrow CH_3COO^-(aq)+NH_4^+(aq)$

here underlined is $HCH_3CO_2$

A. Brønsted-Lowry acid

B. Brønsted-Lowry base

C. Lewis acid

D. Lewis base

2. $BH_3(aq)+NH_3(aq)\rightarrow BH_3NH_3(aq)$

Here underlined is $NH_3$

A. Brønsted-Lowry acid

B. Brønsted-Lowry base

C. Lewis acid

D. Lewis base

3. $HNO_2(aq)+C_2H_5NH_2(aq)\rightarrow NO_2^-(aq) + C_2H_5NH_3^+(aq)$

Here underlined is $C_2H_5NH_2$

A. Brønsted-Lowry acid

B. Brønsted-Lowry base

C. Lewis acid

D. Lewis base

Answer: 1. Brønsted-Lowry acid

2. Lewis base

3. Brønsted-Lowry base

Explanation:

According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

1. $HCH_3CO_2(aq)+NH_3(aq)\rightarrow CH_3CO^{2-}(aq)+NH_4^+aq)$

As $HCH_3CO_2(aq)$ is donating a proton , it acts as a bronsted acid.

2. $BH_3(aq)+NH_3(aq)\rightarrow BH_3NH_3(aq)$

As $NH_3$ contains a lone pair of electron on nitrogen , it can easily donate electrons to $BH_3$ and act as lewi base.

3. $HNO_2(aq)+C_2H_5NH_2(aq)\rightarrow NO_2^-(aq) + C_2H_5NH_3^+(aq)$

As $C_2H_5NH_2(aq)$ is accepting a proton , it acts as a bronsted base.

7 0

3 years ago

Determine whether each of the descriptions of matter describes a heterogeneous mixture, a homogeneous mixture, or a pure substan

lorasvet [3.4K]

Answer: a. two substances present; two phases present : Heterogeneous mixture

b. two substances present; one phase present : Homogeneous mixture

c. one substance present; one phase present : pure substance.

d. one substance present; two phases present: Heterogeneous mixture

Explanation:

A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means.

Mixture is a substance which contains two or more than two types of components and they can be separated by physical means as well.

Homogeneous mixtures: It is a mixture that has uniform composition throughout the solution and the particle size or shapes are not different. There is no physical boundary between the dispersed phase and dispersion medium.

Heterogeneous mixtures: It is a mixture that has non-uniform composition throughout the solution and the particle size or shapes are also different. There is a physical boundary between the dispersed phase and dispersion medium.

5 0

3 years ago

Treatment of butanedioic (succinic) anhydride with ammonia at elevated temperature leads to a compound of molecular formula C4H5

artcher [175]

Answer:

The product is Methyl cyanoacetate

Explanation: see structure attached

5 0

3 years ago