Answer:
Molecules are speeding up as boiling occurs.
Explanation:
We have three states of matter;solid liquid and gas. Substances are found in these different states of matter according to the degree of energy and velocity of its particles. Highly energetic particles moving at high velocities are found in the gaseous state. Less energetic particles moving at lesser velocities due to intermolecular forces are found in the liquid state while particles with the least degree of freedom are found in the solid state. Solid particles do not translate but can vibrate or rotate about a fixed position.
When a liquid boils, particles at the surface of the liquid acquire sufficient energy and escape the surface of the liquid. This is because, as energy is supplied in the form of heat during boiling, molecules acquire sufficient energy to speed up their molecular motion and escape the liquid surface as vapour.
When ice melts, the physicals state changes from solid to liquid. The energy or the heat required (q) required to change a unit mass (m) of a substance from solid to liquid is known as the enthalpy or heat of fusion (ΔHf). The variables; q, m and ΔHf are related as:
q = m * ΔHf
the mass of ice m = 65 g
the heat of fusion of water at 0C = ΔHf = 334 J/g
Therefore: q = 65 g * 334 J/g = 21710 J
Now:
4.184 J = 1 cal
which implies that: 21710 J = 1 cal * 21710 J/4.184 J = 5188.8 cal
Hence the heat required is 5188.8 cal or 5.2 Kcal (approx)
<h3><u>Answer;</u></h3>
Exothermic chemical reaction
<h3><u>Explanation;</u></h3>
- Exothermic reactions are chemical reactions where the products have less energy that the reactants.
- Exothermic reactions give off energy, usually in the form of heat, while endothermic reactions absorb energy.
- The combustion of propane is definitely an exothermic reaction because it generates a lot of heat.
Answer:
Molecular formula → PbSO₄ → Lead sulfate
Option c.
Explanation:
The % percent composition indicates that in 100 g of compound we have:
68.3 g of Pb, 10.6 g of S and (100 - 68.3 - 10.6) = 21.1 g of O
We divide each element by the molar mass:
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
We divide each mol by the lowest value to determine, the molecular formula
0.329 / 0.329 = 1 Pb
0.331 / 0.329 = 1 S
1.32 / 0.329 = 4 O
Molecular formula → PbSO₄ → Lead sulfate
