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3 years ago

On the Kelvin temperature scale, which value approximately represents the freezing point of water?

Chemistry

1 answer:

kupik [55]3 years ago

8 0

Answer: freezing point of water 273.15K, boiling point of water 373.15 K

Explanation:

The Kelvin scale starts at the lowest possible temperature, absolute zero. This is 0 Kelvins (K)= -273.15 deg C. Hence water freezes at 0 deg C = 273.15 K and boils at 100 deg C = 373.15 K

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Consider the statement: “The temperature of the land is an important factor for the ripening of oranges, because it affects the

Alexxx [7]

Physical Properties: Physical properties can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter. so physical changes are the change in temperature of the land and the evaporation of water and change humidity of the air. chemical change is the ripening of the orange

7 0

3 years ago

Hydrogen fluoride is used in the manufacture of Freons (which destroy ozone in the stratosphere) and in the production of alumin

Lerok [7]

Answer: The percentage yield of HF is 73.36 %

Explanation:

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

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ....(1)

For calcium fluoride:

Given mass of calcium fluoride = 6.25 kg = 6250 g (Conversion factor: 1 kg = 1000 g)

Molar mass of calcium fluoride = 78.07 g/mol

Putting values in above equation, we get:

$\text{Moles of calcium fluoride}=\frac{6250g}{78.07g/mol}=80.05mol$

For the given chemical reaction:

$CaF_2+H_2SO_4\rightarrow CaSO_4+2HF$

By Stoichiometry of the reaction:

1 mole of calcium fluoride produces 2 moles of hydrofluoric acid

So, 80.05 moles of calcium fluoride will produce = $\frac{2}{1}\times 80.05=160.1mol$ of hydrofluoric acid

Now, calculating the theoretical yield of hydrofluoric acid using equation 1, we get:

Moles of of hydrofluoric acid = 160.1 moles

Molar mass of hydrofluoric acid = 20.01 g/mol

Putting values in equation 1, we get:

$160.1mol=\frac{\text{Theoretical yield of hydrofluoric acid}}{20.01g/mol}=3203.6g=3.20kg$

To calculate the percentage yield of hydrofluoric acid, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

Experimental yield of hydrofluoric acid = 2.35 kg

Theoretical yield of hydrofluoric acid = 3.20 kg

Putting values in above equation, we get:

$\%\text{ yield of hydrofluoric acid}=\frac{2.35g}{3.20g}\times 100\\\\\% \text{yield of hydrofluoric acid}=73.36\%$

Hence, the percentage yield of HF is 73.36 %

4 0

3 years ago

Why are some alkali metals stored under oil?

Dahasolnce [82]

due to there reactive rate?

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3 years ago

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How many moles of KCLO4 can be produced with 3.45 moles of NaCl. Assume all other reactants are in excess

ycow [4]

NOTE question is incorrect: The question should be:
How many moles of KCLO4 can be produced with 3.45 moles of KCl. Assume all other reactants are in excess.
.......................................................................................................................

The reaction involving formation of KClO4 is

NaClO4 + KCl → KClO4 + NaCl

From above reaction, it can be seen that 1 mole of NaClO4 reacts with 1 mole of KCl to generate 1 mole of KClO4

Thus, if all other reactant are in excess, 3.45 moles of KCl will react with 3.45 moles of NaClO4 to form 3.45 moles of KClO4.

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3 years ago

Which of the following has the greatest first ionization energy: F,Li, Rb, or Fr?

Karolina [17]

B. Flourine

Flourine has one of the highest ionization energies because it is so close to getting a full octet with eight atoms. It doesn't want to lose but rather gain an atom. On the periodic table, ionization energy increases as you head towards the top and to the right.

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4 years ago

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