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Andrew [12]
2 years ago
10

ITEM BANK: Move to Bottom

Chemistry
1 answer:
snow_tiger [21]2 years ago
5 0
  1. Compounds are formed when two or more <u>elements</u> are chemically combined.
  2. When these elements are <u>chemically</u> combined, a new substance is formed with new chemical and physical <u>properties</u>.
  3. An element is a <u>pure</u> substance that cannot be separated into simpler substances by <u>physical</u> or chemical means.
  4. A compound is two or more elements <u>combined</u> chemically to produce a new substance.
  5. When two or more elements chemically combine, the compound has new properties, different from the chemical and physical properties of the <u>original</u> elements.

<h3>What is a chemical element?</h3>

A chemical element can be defined as a pure substance which comprises atoms that have the same atomic number (number of protons) in its nuclei and as such it is the primary constituent of matter.

Generally, some examples of a chemical element include the following:

  1. Argon.
  2. Sodium.
  3. Carbon.
  4. Oxygen.
  5. Hydrogen.
  6. Phosphorus
  7. Copper
  8. Aluminum
  9. Potassium
  10. Magnesium

<h3>What is a pure substance?</h3>

A pure substance can be defined as a single sample of matter that cannot be separated into other kinds of matter through the use of any physical or chemical separating technique because it has distinct chemical properties and a definite and constant composition.

Read more on pure substances here: brainly.com/question/2056940

#SPJ1

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Calculate the standard entropy of vaporization of ethanol, C2H5OH, at 285.0 K, given that the molar heat capacity at constant pr
MArishka [77]

Answer: The standard entropy of vaporization of ethanol is 0.275 J/K

Explanation:

C_2H_5OH(l)\rightleftharpoons C_2H_5OH(g)

Using Gibbs Helmholtz equation:

\Delta G=\Delta H-T\Delta S

For a phase change, the reaction remains in equilibrium, thus \Delta G=0

\Delta H=T\Delta S

Given: Temperature = 285.0 K

\Delta H=78.3J/mol

Putting the values in the equation:

78.3J=285.0K\times \Delta S

\Delta S=0.275J/K

Thus  the standard entropy of vaporization of ethanol is 0.275 J/K

4 0
3 years ago
Number of moles in 1.806*10^22 molecules of nitrogen
Fynjy0 [20]
Hi there!

• Avogadro's number = 6.023 × 10²³
• No.of molecules in N = 1.806 × 10²²  [ Given ]

It's known that :-

Number of molecules = Moles × Avogadro's number

=> 1.806 × 10²² = Mol. × 6.023 × 10²³

=> Mole = \dfrac {1.806 \cdot 10^{22} }{6.023 \cdot 10^{23} }

=> Moles = 0.03 mol.

Hence, 0.03 mol. is th' required answer.

~ Hope it helps!
3 0
3 years ago
Negative ions are usually formed from: metals nonmetals
Lelechka [254]
Non metals are electronegative in nature whereas metals are electropositive. A non-metal accepts electron and gains negative charge whereas metals lose eletrons and gains positive charge. Hence correct answer is non-metals. Hope this helps!
3 0
3 years ago
Read 2 more answers
Which method is most likely used to identify what happened before the start of the paleozoic era?
vodka [1.7K]
Scientist examine fossil evidence during the pre-time yes researching about the things at the pre-Cambrian time might help them to identify what would’ve happened before Paleozoic era
6 0
2 years ago
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Calculate the AHrxn from the AH of formation for the following reaction. C2H4(g) + 302(g) 2C02(g) + 2H20(1). Formation AH values
RSB [31]

Answer

A. -1305 kJ

Explanation

Given:

Equation: C2H4(g) + 302(g) ---- > 2C02(g) + 2H20(l).

Formation ΔH values:

​​for C2H4(g) = 52.30 kJ/mol,

for 02(g) = 0 kJ/mol,

for CO2(g) = -393.5 kJ/mol, and

for H20(1) = -285.8kJ/mol.

What to find:

The ΔHrxn from the ΔH of formation for the given reaction.

Step-by-step solution:

ΔHrxn = (Sum of ΔH formation for the product) - (Sum of ΔH formation for the reactants).

ΔHrxn = (ΔH for 2CO2(g) + ΔH for 2H2O(l)) + (ΔH for C2H4(g) + ΔH for 3O2(g))

ΔHrxn = [(2 x -393.5) + (2 x -285.8)] + [52.30 + (3 x 0)]

ΔHrxn =(-787.0 - 571.6) + (52.30 + 0)

ΔHrxn = -1358.6 + 52.30

ΔHrxn = -1306.3 kJ

so the closest answer is A. -1305 kJ

4 0
9 months ago
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