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3 years ago

What is the difference between a physical change and a chemical change? (2 points)

Chemistry

2 answers:

charle [14.2K]3 years ago

7 0

A physical change does not change the identity of the substance but the chemical change does.

Example

If you tear or shred a piece of paper it is still paper, but if you pour chemicals on it it will probably change to something else.

hodyreva [135]3 years ago

3 0

Answer:

Explanation:

A physical change does not change the identity of the substance but the chemical change does.

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What is the heat of vaporization of ethanol, given that ethanol has a normal boiling point of 63.5°C and the vapor pressure of e

Serjik [45]

Explanation:

According to Clausius-Claperyon equation,

$ln (\frac{P_{2}}{P_{1}}) = \frac{-\text{heat of vaporization}}{R} \times [\frac{1}{T_{2}} - \frac{1}{T_{1}}]$

The given data is as follows.

$T_{1} = 63.5^{o}C$ = (63.5 + 273) K

= 336.6 K

$T_{2} = 78^{o}C$ = (78 + 273) K

= 351 K

$P_{1}$ = 1 atm, $P_{2}$ = ?

Putting the given values into the above equation as follows.

$ln (\frac{P_{2}}{P_{1}}) = \frac{-\text{heat of vaporization}}{R} \times [\frac{1}{T_{2}} - \frac{1}{T_{1}}]$

$ln (\frac{1.75 atm}{1 atm}) = \frac{-\text{heat of vaporization}}{8.314 J/mol K} \times [\frac{1}{351 K} - \frac{1}{336.6 K}]$

$\Delta H$ = $\frac{0.559}{1.466 \times 10^{-4}} J/mol$

= $0.38131 \times 10^{4} J/mol$

= 3813.1 J/mol

Thus, we can conclude that the heat of vaporization of ethanol is 3813.1 J/mol.

4 0

3 years ago

A dextrose/saline aqueaout solution doctors commonly use to replace fluids in the body contains 1.75g/L NaCl and 40.0g/L dextros

qwelly [4]

<em>Mixed molarity = 0.25 M</em>

<em>Osmotic pressure solution: 6.15 atm</em>

<h3><em>Further explanation</em></h3>

Osmotic pressure is the minimum pressure given to the solution so that there is no osmotic displacement from a more dilute solution to a more concentrated solution.

General formula:

$\large{\boxed {\bold {\pi \: = \: M \: x \: R \: x \: T}}}$

π = osmotic pressure (atm)

M = solution concentration (mol / l)

R = constant = 0.08205 L atm mol-1 K-1

T = Temperature (Kelvin)

Mixing solution

To find the molarity of the mixed solution we can use the following formula:

Vc. Mc = V1.M1 + V2.M2

where

Mc =Mixed molarity

Vc = mixed volume

Mr. NaCl = 58.5

Mr. Dextrose = C₆H₁₂O₆ = 180

mole NaCl = gram / Mr

mole NaCl = 1.75 / 58.5 = 0.03

Dextrose mole = 40/180 = 0.22

Assuming 1 liter of solution

M mixture = mole NaCl + mole dextrose / 1 liter

M mixture = 0.03 + 0.22 / 1 L

M mix = 0.25 M

T = 25 + 273 = 298 K

The osmosis pressure of the solution becomes:

π = 0.25. 0.0825. 298 = 6.15 atm

<h3><em>Learn more</em></h3>

The osmotic pressure brainly.com/question/8195553

<h3><em>Answer details </em></h3>

Grade: Senior High School

Subject: Chemistry

Chapter: Colligative property

Keywords: osmotic pressure, molarity, mole,dextrose, NaCl

7 0

3 years ago

What substance is most likely the most dense chlorine,oxygen,bromine, and silver

Reil [10]

Silver is the densest as it is lower on the periodic table containing more protons and nuetrons and electrons

7 0

3 years ago

Read 2 more answers

Which of the following is an example of a physical change ?

inessss [21]

A. A piece of Iron being heated until it melts
Because it goes from solid to liquid.
A physical change is changing from solid to a liquid, a liquid to a gas, a gas to a liquid, a liquid to a solid, a solid to a gas, or a gas to a solid.

3 0

3 years ago

What are memory B cells and memory T cell

UNO [17]

Answer: Memory B and memory T cells are types of lymphocytes.

Explanation:

Memory B cells forms the part of adaptive immune system. These cells develop inside the germinal centers of the secondary lymphoid organs. These cells circulate in the blood. These are produced by the bone marrow and can be found in tonsil and spleen. Memory B cells are responsible for recognizing previous infections with a foreign antigen and prepare antibody against the new infection. Memory T cells recognize the antigen lived in the body for longer and produce quick response against it on second exposure. These are one of the types of T lymphocytes.

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3 years ago