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3 years ago

If the statement is true, select True. If it is false, select False.

Chemistry

1 answer:

defon3 years ago

5 0

Answer:

False, since boiling is a physical change of state. Although it is at 100°C, it is not a chemical property.

Explanation:

Hope this helped!

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A rock contains 0.623 mg of 206Pb for every 1.000 mg of 238U present. Assuming that no lead was originally present, that all the

maxonik [38]

Answer:

t = 3,496x10⁹ years

Explanation:

The decay of ²³⁸U is:

²³⁸U → ²⁰⁶Pb + 8He + 6e⁻

Moles of ²⁰⁶Pb presents in 0,623mg are:

0,623x10⁻³g×(1mol / 206g) = 3,02x10⁻⁶ moles of ²⁰⁶Pb.

These moles are equals to moles of ²³⁸U before decay, that means, 3,02x10⁻⁶ moles²³⁸U

In grams:

3,02x10⁻⁶ moles²³⁸U× (238g / 1mol) = 7,20x10⁻⁴ g ²³⁸U = 0,720 mg²³⁸U

That means initial ²³⁸U was 1,000mg + 0,720mg = 1,720mg

Applying the formula:

ln (N₀/N) t₁₂ = t ln2

Where N₀ is initial amount of uranium (1,720mg), N is concentration of uranium (1,000mg), half-life time is a constant (t₁₂= 4,468x10⁹ years) and t is the time transcurred for the reaction. Replacing:

ln(1,720/1)*4,468x10⁹ years = t ln2

t = 3,496x10⁹ years

I hope it helps!

6 0

3 years ago

How many atoms are present in 179.0 g of iridium? include units please:)!

denpristay [2]

Answer:

179.0 g of iridium (1 mol / 192.217 g) ( 6.022 x 10^23 atoms / 1 mol ) = 5.61 x 10^23 atoms of iridium

Explanation:

5 0

4 years ago

Read 2 more answers

What element on the periodic table has a period of 3, and a group of 5?

k0ka [10]

Answer:

The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block.

Explanation:

3 0

3 years ago

Read 2 more answers

5.50g of a certain Compound X, known to be made of carbon, hydrogen and perhaps oxygen, and to have a molecular molar mass of 13

Nimfa-mama [501]

Answer:

The molecular formula is C8H8O2

Explanation:

Step 1: Data given

Mass of compound X = 5.50 grams

Mass of CO2 = 14.24 grams

Molar mass of CO2 = 44.01 g/mol

Mass of H2O = 2.91 grams

Molar mass H2O = 18.02 g/mol

Molar mass C = 12.01 g/mol

Molar mass O = 16.0 g/mol

Molar mass H = 1.01 g/mol

Molar mass of the compound = 136 g/mol

Step 2: Calculate moles CO2

Moles CO2 = 14.24 grams / 44.01 g/mol

Moles CO2 = 0.324 moles

Step 3: Calculate moles C

For 1 mol cO2 we have 1 mol C

For 0.324 moles CO2 we have 0.324 moles C

Step 4: Calculate mass C

Mass C = 0.324 moles * 12.01 g/mol

Mass C = 3.89 grams

Step 5: Calculate moles H2O

Moles H2O = 2.91 grams / 18.02 g/mol

Moles H2O = 0.161 moles

Step 6: Calculate moles H

For 1 mol H2O we have 2 moles H

For 0.161 moles H2O we have 2*0.161 = 0.322 moles H

Step 7: Calculate mass H

Mass H = 0.322 moles * 1.01 g/mol

Mass H = 0.325 grams

Step 8: Calculate mass O

Mass O = 5.50 grams - 3.89 grams - 0.325 grams

MAss O = 1.285 grams

Step 9: Calculate moles O

Moles O = 1.285 grams / 16.0 g/mol

Moles O = 0.0803 moles

Step 10: Calculate mol ratio

We divide by the smallest amount of moles

C: 0.324 moles / 0.0803 moles = 4

H: 0.322 moles / 0.0803 moles = 4

O: 0.0803 moles / 0.0803 moles = 1

The empirical formula is C4H4O

The molar mass of this empirical formula is 68 g/mol

Step 11: Calculate the molecular formula

We have to multiply the empirical formula by n

n = 136 g/mol / 68 g/mol

n = 2

We have to multiply the empirical formula by 2

Molecular formula = 2*(C4H4O) = C8H8O2

The molecular formula is C8H8O2

3 0

4 years ago

Describe three ways that individuals can combat global warming.

vagabundo [1.1K]

They could stop driving cars and opt in for walking or riding a bike, drive an electric car because they don't take gas. They could also get their electricity from renewable resources such as electricity from wind mills and solar panels and hydro-electric.

8 0

3 years ago