Balancing equations and masscalculations self

Self Test on Balancing Equations and Mass Calculations

1. Assign oxidation numbers to the "*" marked atoms in the following ions and molecules.

____Cl in NaCl* ____O in H₂O* ____S in
S^*O₂

____N in N^*O₂^1- ____H in H₂^* ____C in
C^*O

____C in C^*O₃^2- ____N in N^*O₃^1- ____C in
C^*O₂

2. Balance and classify each of the following reactions. Acid-base, oxidation-reduction, precipitation. Use a solubility table to identify insoluble and soluble products. State the physical forms for each product. (l), liquid; (g), gas; (s), solid; (aq), aqueous.

C₁₂H₂₆(l) + O₂(g) ----> CO₂(g) + H₂O(g)

Si₂H₆(g) + O₂(g) ----> H₂O(g) + SiO₂(s)

Na₂S(aq) + ZnCl₂(aq) ----> ZnS(s) + NaCl(aq)

Na₂CO₃(aq) + HNO₃(aq) ----> NaNO₃(aq) + CO₂(g) + H₂O(l)

3.	How many moles of H₂ are needed to hydrogenate 10 moles of the unsaturated fatty acid C₁₄H₂₆CO₂H and form the saturated fatty acid C₁₄H₃₀CO₂H ? Hint balance the equation first. Show work

____C₁₄H₂₆CO₂H + ____ H₂ -----> _____C₁₄H₃₀CO₂H

4.	What is the number of moles of product formed, when 825 grams of S₈(s) reacts with unlimited grams of Cl₂(g)?

S₈(l) + 4 Cl₂(g) -----> 4 S₂Cl₂(g)

Explain why reactions do not typically give 100% yields. What is the percent yield for the production of diborane, B₂H₆? The predicted yield is 126 g and the actual yield was 81 g? The equation for the reaction is written below.

2 NaBH₄(s) + I₂(s) ----> B₂H₆(g) + 2 NaI(s) + H₂(g)

6.	Phosphoric acid is made in industry by reacting sulfuric acid with mineral phosphates. The reaction between the mineral apatite, Ca₅(PO₄)₃F, and sulfuric acid is written below.

5 H₂SO₄(aq) + Ca₅(PO₄)₃F + 10 H₂O ----> HF + 3 H₃PO₄+ CaSO₄• 2 H₂O

What is the actual yield for the reaction if the theoretical yield is 109 pounds of phosphoric acid, H₃PO₄, and the percent yield normally is 83 %?

7.	What is the limiting reagent if 100. moles of hydrogen sulfide, H₂S, is mixed with 240. moles of sodium hydroxide, NaOH, according to the following reaction? Show work .

H₂S+ 2 NaOH ----> Na₂S + 2 H₂O

8.	What is the limiting reagent if 100. grams of carbon disulfide, CS₂, is mixed with 120. grams of sodium hydroxide, NaOH, according to the following reaction? Show work .

3 CS₂ + 6 NaOH ----> 2 Na₂CS₃ + Na₂CO₃ + 3 H₂O

1. Assign oxidation numbers to the "*" marked atoms in the following ions and molecules.
____Cl in	NaCl*	____O in	H₂O*	____S in	S^*O₂
____N in	N^*O₂^1-	____H in	H₂^*	____C in	C^*O
____C in	C^*O₃^2-	____N in	N^*O₃^1-	____C in	C^*O₂