Write the symbol for each of the following ions:
(a) the ion with a 1+ charge, atomic number 55, and mass number 133
(b) the ion with 54 electrons, 53 protons, and 74 neutrons
(c) the ion with 24 electrons, 30 neutrons, and a 3+ charge
According to the following reaction, how many grams of water will be formed upon the complete reaction of 23.3 grams of iron(III) oxide with excess hydrochloric acid?
6HCl (aq) + Fe2O3 (s) 3H2O (l) + 2FeCl3 (aq)
Consider the titration of a 25.0 mL sample of 0.1 75 mol L- 1 CH3NH2 with 0. 150 mol L-1 HBr. Determine each quantity: Show all the chemical equations used.
a. the initial pH
b. the volume of added acid required to reach the equivalence point
c. the pH at 5.0 mL of added acid
d. the pH at one-half of the equivalence point
e. the pH at the equivalence point
f. the pH after adding 5.0 mL of acid beyond the equivalence point
25 cm3 of a solution containing T grams of K2CO3 in 1000 cm3 of solution were completely neutralized by 20.00 cm3 of a solution containing 0.025 mole of H2SO4 in 1 dm3 of solution
Calculate the :
(a) concentration of K2CO3 solution in moldm-3
(b) Value of T
(c) mass of K2SO4 formed
(d) volume of CO2 evolved at STP
(e) number of H2O molecules
Given the following thermochemical equations:
1.) 4NH3)+302(g) → 2N₂(g) + 6H₂0 (1) ∆H°-1531 kJ
2.) N₂O(g) + H₂(g) → N₂(g) + H₂O(0) ∆H°-367.4 k]
3.) H₂(0)+02 (0)→ H₂0 (1)
∆H°= -285.9 kJ
Find the value of AH" for the reaction:
2NH3(g) + 3N₂0(g) → 4N₂(g) + 3H₂O(1)
Chlorine trifluoride is a colorless, poisonous, and corrosive gas. It is produced from the reaction between chlorine fluoride and fluorine gas.
CIF(g) + F2 (g) → CLF3 (9)
Determine the ∆H° for the overall reaction based on the three-step thermochemical process below:
1.) 2CLF(g) + O2(g) → Cl₂0(g) + F₂0 (g) ∆°H-167.5 k]
2.) 2C1F3(g) +202(g) → Cl₂0(g) + 3F₂0(g)
∆H° =-341.4 k]
3.) 3F₂0)→2F2 (g) + O2(g)
∆H° = 43.4 kJ
A system absorbs 50J of heat during a transformation. Determine the change in internal energy if
the system perform, (a) 15J and (b) 65J of work on the surrounding.
Find the ∆E
a) When 175J of work is done on a system that evolves 50J of heat to the surrounding.
b) When a gas absorbs 28kJ of heat and 13kJ of work done on it.
2.83 g of a sample of haematite iron ore [iron (III) oxide, Fe2O3] were dissolved in concentrated hydrochloric acid and the solution diluted to 250 cm3. 25.0 cm3 of this solution was reduced with tin(II) chloride (which is oxidised to Sn4+ in the process) to form a solution of iron(II) ions. This solution of iron(II) ions required 26.4 cm3 of a 0.0200 mol/dm3 potassium dichromate(VI) solution for complete oxidation back to iron(III) ions.
(a) given the half–cell reactions
(i) Sn4+(aq) + 2e– ==> Sn2+(aq)
and (ii) Cr2O72–(aq) + 14H+(aq) + 6e– ==> 2Cr3+(aq) + 7H2O(l)
deduce the fully balanced redox equations for the reactions
(i) the reduction of iron(III) ions by tin(II) ions
(ii) the oxidation of iron(II) ions by the dichromate(VI) ion
(b) Calculate the percentage of iron(III) oxide in the ore.
7. Use the oxidation number method to balance the following equations:
a) Al(s) + H2SO4 (aq) Al2(SO4)3 (aq) + H2 (g)
b) PbS(s) + O2(g) PbO (s) + SO2 (g)