help with 3 chem problems please?

Question

The balanced equation for the reaction between potassium and water to produce potassium hydroxide and hydrogen is
K + 2H2O → K(OH)2 + H2
2K + 3H2O → 2KOH + 2H2
K2 + 2H2O → KOH + H2
2K + 2H2O → 2KOH + H2

The coefficient that should go in front of O2 in the equation C3H6 + O2 → CO2 + H2O
4
5
9
8


What is the molecular mass of lithium oxide? (Remember to first make lithium oxide balanced with positive and negative charges.)
29.9 amu
22.9 amu
45.8 amu
38.9 amu

Answer 1

A. 2K + 2H2O --> 2KOH + H2

B. 2C3H6 + 9O2 --> 6CO2 + 6H2O, so 9 is the right answer.

C. Li has an oxidation number of +1 and O has an oxidation number of -2, so the formula for lithium oxide is Li2O. The atomic mass of Li equals 6.95 and of oxygen equals 16 so the molecular mass of Li2O is:

2*6.9 + 16 = 29.9

Answer 2

2K + 2 H2O --> 2KOH + H2 is balanced

2C3H6 + 9 O2 --> 6CO2 + 6H2O is balanced (if you have difficulty in balancing combustion equations, sometimes it is helpful to double the hydrocarbon at the start to insure that you have an even number of oxygens in the products).

Li2O = 2(6.95) + 15.99 = 29.9 {lithium is monovalent [+1] and the oxide ion is divalent [-2]}

Answer 3

Na(s) + 2 HOH(l) -----------------> NaOH(aq) + H2(g Convert the mass of Na into moles. moles = mass / Molar mass. 4.6 g / 22.ninety 9 g/mol = 0.2 hundred moles Use the mole ratio from the balanced equation to locate the style of moles of H2 produced. The equation is balanced for a million mole of Na to offer a million mole of H2. that's a a million to a million ratio. hence you should additionally get 0.2 hundred moles of H2 At STP which will equivalent to 0.2 hundred moles x 22.4 L/mol = 4.5 L 2CO(g) + O2(g) ---------> 2 CO2(g) 5 L of CO at STP is 5 / 22.4 L/mol = 0.00390 moles The equation says which you will get the comparable style of moles of CO2 so moles of CO2 = 0.00390 volume hence is 22.4 L/mol x 0.00390 moles = 0.087 L or 87 mL i'm not sure what you advise by employing the final question.

Answer 4

1.2K + 2H2O → KOH + H2
2. 2
3. 29.9 amu