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3 years ago

Isotopes have similar

Chemistry

1 answer:

zysi [14]3 years ago

3 0

Answer:

To my knowledge, it should be the last 2

Explanation:

1. Incorrect as atoms make up elements when they all have the same properties

2. Incorrect, an element can have other similar elements, they're ordered like that in the periodic table

3. Correct as atoms are made up of mostly space, with mass concentrated at the center of the atom, the nucleus and a few tiny electrons in orbit as proved by Rutherfords alpha particle scattering experiment

4. Correct, Atoms are known as the building blocks of matter

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Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin pla

RSB [31]

<u>Answer:</u> The enthalpy change of the reaction is -27. kJ/mol

<u>Explanation:</u>

To calculate the mass of water, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of water = 1 g/mL

Volume of water = 25.0 mL

Putting values in above equation, we get:

$1g/mL=\frac{\text{Mass of water}}{25.0mL}\\\\\text{Mass of water}=(1g/mL\times 25.0mL)=25g$

To calculate the heat released by the reaction, we use the equation:

$q=mc\Delta T$

where,

q = heat released

m = Total mass = [1.25 + 25] = 26.25 g

c = heat capacity of water = 4.18 J/g°C

$\Delta T$ = change in temperature = $T_2-T_1=(21.9-25.8)^oC=-3.9^oC$

Putting values in above equation, we get:

$q=26.25g\tiimes 4.18J/g^oC\times (-3.9^oC)=-427.9J=-0.428kJ$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of ammonium nitrate = 1.25 g

Molar mass of ammonium nitrate = 80 g/mol

Putting values in above equation, we get:

$\text{Moles of ammonium nitrate}=\frac{1.25g}{80g/mol}=0.0156mol$

To calculate the enthalpy change of the reaction, we use the equation:

$\Delta H_{rxn}=\frac{q}{n}$

where,

q = amount of heat released = -0.428 kJ

n = number of moles = 0.0156 moles

$\Delta H_{rxn}$ = enthalpy change of the reaction

Putting values in above equation, we get:

$\Delta H_{rxn}=\frac{-0.428kJ}{0.0156mol}=-27.44kJ/mol$

Hence, the enthalpy change of the reaction is -27. kJ/mol

4 0

4 years ago

Non-living factors in an ecosystem are ______.

mash [69]

Answer:

B. abiotic

Explanation:

in biology and ecology, abiotic components or abiotic factors are non living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems.

5 0

3 years ago

What Does M mean chemistry

Hunter-Best [27]

Molybdenum in periodic table

Molarity definition

4 0

3 years ago

Read 2 more answers

Explain your observations in term of how tempurature affects paritcle motion and how liquid changes to a solid

Rus_ich [418]

Answer:

See explanation

Explanation:

Temperature is defined as a measure of the average kinetic energy of the molecules of a body.

When a substance is heated, the kinetic energy of its molecules increases as the temperature increases; hence the particles of the substance moves faster with increasing temperature.

When heat is withdrawn from a liquid, the temperature decreases and the average kinetic energy of the molecules decreases. The molecules become less energetic hence the liquid changes into solid

4 0

3 years ago

Which of the following has the most H+ ions in its solution?

devlian [24]

Answer:

Explanation:

The lower the pH the greater the concentration of H+ ions. Hydrochloric acid with a pH of 1 is a strong acid and is highly ionised in solution. It has the most H+ ions

7 0

4 years ago