Fireworks owe their colors to reactions of combustion of the metals present. When Mg and Al burn, they emit a white bright light, whereas iron emits a gold light. Besides metals, oxygen is necesary for the combustion. The decomposition reactions of barium nitrate and potassium chlorate provide this element. At the same time, barium can burn emitting a green light.
(a) Barium nitrate is a <em>salt</em> formed by the <em>cation</em> barium Ba²⁺ and the <em>anion</em> nitrate NO₃⁻. Its formula is Ba(NO₃)₂. Potassium chlorate is a <em>salt</em> formed by the <em>cation</em> potassium K⁺ and the <em>anion</em> chlorate ClO₃⁻. Its formula is KClO₃.
(b) The balanced equation for the decomposition of potassium chloride is:
2KClO₃(s) ⇄ 2KCl(s) + 3O₂(g)
(c) The balanced equation for the decomposition of barium nitrate is:
Ba(NO₃)₂(s) ⇄ BaO(s) + N₂(g) + 3O₂(g)
(d) The balanced equations of metals with oxygen to form metal oxides are:
- 2 Mg(s) + O₂(g) ⇄ 2 MgO(s)
- 4 Al(s) + 3 O₂(g) ⇄ 2 Al₂O₃(s)
- 4 Fe(s) + 3 O₂(g) ⇄ 2 Fe₂O₃(s)
Answer:
Explanation:
Given parameters:
Mass of CuCl₂ = 2.50g
Mass of Al = 0.50g
Unknown:
Number of moles of CuCl₂ and Al = ?
Solution:
To solve this problem, we must understand that the number of moles is a fundamental property used in stoichiometry calculations.
Number of moles = 
Molar mass of CuCl₂ = 63.6 + 2(35.5) = 134.5g/mole
Molar mass of Al = 26.98g/mole
Number of moles of CuCl₂ = 
= 0.019moles
Number of moles of Al = 
= 0.019moles
Answer:
fH = - 3,255.7 kJ/mol
Explanation:
Because the bomb calorimeter is adiabatic (q =0), there'is no heat inside or outside it, so the heat flow from the combustion plus the heat flow of the system (bomb, water, and the contents) must be 0.
Qsystem + Qcombustion = 0
Qsystem = heat capacity*ΔT
10000*(25.000 - 20.826) + Qc = 0
Qcombustion = - 41,740 J = - 41.74 kJ
So, the enthaply of formation of benzene (fH) at 298.15 K (25.000 ºC) is the heat of the combustion, divided by the number of moles of it. The molar mass od benzene is: 6x12 g/mol of C + 6x1 g/mol of H = 78 g/mol, and:
n = mass/molar mass = 1/ 78
n = 0.01282 mol
fH = -41.74/0.01282
fH = - 3,255.7 kJ/mol
Explanation:
a) In 1 mole of methane there are 4 moles of hydrogen atom
Atomic mass of 1 mole of hydrogen atom = 1 g
Mass of hydrogen in 1 mole of methane = 4 × 1 g = 4 g
b) In 1 mole of chloroform there are 1 mole of hydrogen atom
Atomic mass of 1 mole of hydrogen atom = 1 g
Mass of hydrogen in 1 mole of methane = 1× 1 g = 1 g
c) In 1 mole of 
there are 10 moles of hydrogen atom
Atomic mass of 1 mole of hydrogen atom = 1 g
Mass of hydrogen in 1 mole of = 10 × 1 g = 10 g
d)In 1 mole of 
there are 12 moles of hydrogen atom.
Atomic mass of 1 mole of hydrogen atom = 1 g
Mass of hydrogen in 1 mole of = 12 × 1 g = 12 g
Answer is: osmotic pressure.
Osmotic pressure, alongside the vapor pressure depression, freezing point depression and the boiling point elevation are<span> the </span>colligative properties od solution.
<span>The direction of osmotic pressure is always from the side with the lower concentration (c = n/V) of solute to the side with the higher concentration.</span>
