A geological sample is found to have a Pb-206/U-238 mass ratio of 0.337/1.00. Assuming there was no Pb-206 present when the samp

Solution:

The molecular formula is PbSO₄, indicating lead sulfate

Option c.

Explanation:

The percentage makeup shows that in 100 g of this compound, there are:

68.3 g of Pb, 10.6 g of S, and (100 - 68.3 - 10.6) = 21.1 g of O

To find the moles of each element, we divide by their molar masses:

68.3 g Pb / 207.2 g/mol = 0.329 moles Pb

10.6 g S / 32.06 g/mol = 0.331 moles S

21.1 g O / 16 g/mol = 1.32 moles O

Next, we find the mole ratio by dividing each by the smallest number of moles:

0.329 / 0.329 = 1 Pb

0.331 / 0.329 = 1 S

1.32 / 0.329 = 4 O

Thus, the molecular formula is PbSO₄, representing lead sulfate.

To determine the mass of the lead piece, we use the following equation: Q(heat) = mC delta T, where Q equals 78.0 j, M is the mass we want to find, C is the specific heat capacity (0.130 j/g/C), and delta T shows the temperature difference, set at 9.0 c. Rearranging the formula to solve for M gives us M = Q / c delta T. By substituting in the values, we conclude that M = 78.0 j / (0.130 j/g/C * 9.0 C), calculating this gives us a mass of 66.7 g of lead.

Response: Water is a polar substance, facilitating the dissolution of ionic compounds due to the principle that similar types mix.

Ionic interactions occur between salt and water

Sugar contains hydroxyl groups that can form hydrogen bonds with water molecules.

[Hydrogen bond: this refers to the attraction between a hydrogen atom bonded to a highly electronegative atom (like F, O, or N) and another highly electronegative atom (F, O, or N)]

Thus, due to the presence of hydrogen bonds, sugar dissolves in water.

Clarification: Water molecules are polar, exhibiting partial positive charges on the hydrogen atoms and a partial negative charge on the oxygen atom. This allows them to interact with ionic compounds such as salt (NaCl). These interactions occur through the partial charges on water, which attract opposite charges. When dissolved in water, NaCl dissociates into sodium and chloride ions; sodium ions are surrounded by negatively charged oxygen from water, while chloride ions are surrounded by positively charged hydrogens from water. As a result, salt dissolves in water.

Sugar, being a covalent compound, has bonds where electrons are shared unevenly, creating slight positive and negative charges. This characteristic allows sugar to interact with the polar ends of water, facilitating its dissolution. Therefore, it can be stated that sugar dissolves in water due to both substances being polar.

In summary, water is capable of dissolving most polar or ionic substances, as seen with sugar and salt.

Answer:

Explanation:

Given data:

Initial temperature T₁ = 25.2°C = 298.2K

Initial pressure P₁ = 0.6atm

Final temperature = 72.4°C = 345.4K

What we need to find:

Final pressure = ?

To determine this, we apply a modified version of the combined gas law with constant volume. This simplifies our calculations to:

Here, P and T signify pressure and temperatures, 1 refers to initial and 2 to final temperatures.

Now we can substitute the known variables:

P₂ = 0.7atm

1) reacting hydrochloric acid with nickel:

Balanced molecular equation: Ni(s) + 2HCl(aq) → NiCl₂(aq) + H₂(g).

Ionic equation: Ni(s) + 2H⁺(aq) + 2Cl⁻(aq) → Ni²⁺(aq) + 2Cl⁻(aq) + H₂(g).

Net ionic equation: Ni(s) + 2H⁺(aq) → Ni²⁺(aq) + H₂(g).

In this reaction, nickel undergoes oxidation, changing from an oxidation state of 0 to +2, while hydrogen is reduced from +1 to 0 (H₂).

2) reacting sulfuric acid with iron:

Balanced molecular equation: Fe(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂(g).

Ionic equation: Fe(s) + 2H⁺(aq) + SO₄²⁻(aq) → Fe²⁺(aq) + SO₄²⁻(aq) + H₂(g).

Net ionic equation: Fe(s) + 2H⁺(aq) → Fe²⁺(aq) + H₂(g).

In this scenario, iron is oxidized from an oxidation state of 0 to +2, while hydrogen experiences reduction from +1 to 0 (H₂).

3) hydrobromic acid reacting with magnesium:

Balanced molecular equation: Mg(s) + 2HBr(aq) → MgBr₂(aq) + H₂(g).

Ionic equation: Mg(s) + 2H⁺(aq) + 2Br⁻(aq) → Mg²⁺(aq) + 2Br⁻(aq) + H₂(g).

Net ionic equation: Mg(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂(g).

This reaction sees magnesium oxidized from 0 to +2, and hydrogen reduced from +1 to 0 (H₂).

4) acetic acid reacting with zinc:

Balanced molecular equation: Zn(s) + 2CH₃COOH(aq) → (CH₃COO)₂Zn(aq) + H₂(g).

Ionic equation: Zn(s) + 2H⁺(aq) + 2CH₃COO⁻(aq) → Zn²⁺(aq) + 2CH₃COO⁻(aq) + H₂(g).

Net ionic equation: Zn(s) + 2H⁺(aq) → Zn²⁺(aq) + H₂(g).

Here, zinc gets oxidized from 0 to +2 (Zn²⁺), while hydrogen is reduced from +1 to 0 (H₂).