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3 years ago

Helium and nickel are examples of ________. These

Chemistry

1 answer:

emmasim [6.3K]3 years ago

3 0

Answer:

Elements, in turn, are pure substances—such as nickel, hydrogen, and helium—that make up all kinds of matter.

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What is a physical change

mars1129 [50]

A physical change is a change that can be fixed like cutting wood or tearing paper, or breaking a bone, on the flip side chemical changes cannot be undone, this is like rust on a nail

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3 years ago

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Which element is likely to have the highest thermal conductivity

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sodium element is likely to have the highest thermal conductivity

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4 years ago

One molecule is made of two or more _____ bonded together.

gayaneshka [121]

Answer:

One molecule is made of two or more atoms bonded together.

Explanation:

Molecule is a substance which is made up chemically by two or more same or different atoms. The atoms joint together in a molecule due to a chemical bond. This chemical bond is formed either by mutual sharing of electrons or transfer of electrons between two atoms.

Examples:

A molecule of H₂O (water) is made up of two atoms of Hydrogen and one atom of Oxygen (H-O-H).

A molecule of CO₂ (Carbon Dioxide) is formed when a carbon atom is bonded to two oxygen atoms via a double bonds (O=C=O).

A molecule of N₂ (Nitrogen Gas) is formed between two nitrogen atoms through a triple bond (N≡N).

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3 years ago

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Assume the volume of the crew cabin is 74,000 L. The pressure is maintained at around 1.00 atm, ideally with an 80% nitrogen and

hjlf

Answer:

The number of moles of oxygen present in the crew cabin at any given time is 615.309 moles

Explanation:

The given parameters are;

Volume of the crew cabin = 74,000 L

Pressure of the crew cabin = 1.00 atm

Percentage of nitrogen in the mixture of gases in the cabin = 80%

Percentage of oxygen in the mixture of gases in the cabin = 20%

Temperature of the cabin = 20°C = 293.15 K

Therefore, volume of oxygen in the crew cabin = 20% of 74,000 L

Hence, volume of oxygen in the crew cabin = $\frac{20}{100} \times 74,000 \, L = 14,800 \, L$

From the universal gas equation, we have;

$n = \frac{P \times V}{R \times T}$

Where:

n = Number of moles of oxygen

P = Pressure = 1.00 atm

V = Volume of oxygen = 14,800 L

T = Temperature = 293.15 K

R = Universal Gas Constant = 0.08205 L·atm/(mol·K)

Plugging in the values, we have;

$n = \frac{1 \times 14,800 }{0.08205 \times 293.15 } = 615.309 \, moles$

The number of moles of oxygen present in the crew cabin at any given time = 615.309 moles.

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4 years ago

A 20.38 gram sample of cobalt is heated in the presence of excess sulfur. A metal sulfide is formed with a mass of 31.47 g. Dete

Viefleur [7K]

Answer: The empirical formula of the metal sulfide is $CoBr_{2}$ .

Explanation:

Given: Mass of metal = 20.38 g

Mass of metal sulfide = 31.47 g

Moles is the mass of a substance divided by its molar mass.

So, moles of cobalt (molar mass = 59 g/mol) are as follows.

$Moles = \frac{mass}{molarmass}\\= \frac{20.38 g}{59 g/mol}\\= 0.345 mol$

Moles of bromine (molar mass = 80 g/mol) are as follows.

$Moles = \frac{(31.47 - 20.38) g}{80 g/mol}\\= \frac{11.09 g}{80 g/mol}\\= 0.138 mol$

Now, the ratio of number of moles of cobalt and number of moles of bromine are as follows.

Moles of Co : Moles of Br = 1 : 2

Hence, the empirical formula is $CoBr_{2}$ .

Thus, we can conclude that the empirical formula of the metal sulfide is $CoBr_{2}$ .

6 0

3 years ago