Answer:
Explanation:
Given Rxn =>  4NH₃ + 5O₂ => 4NO + 6H₂O
Given data => 4.23 x 10²² molecules NH₃ => ? molecules NO
Approach: Convert given value in molecules to moles, solve for moles NO by equation ratios in balanced equation. Finish by multiplying moles of NO by Avogadro's Number (= 6.02 x 10²³ molecules/mole) to obtain molecules of NO.
moles NH₃ = 4.23 x 10²² molecules NH₃ / 6.023 x 10²³ molecules/mole
= 0.0703 mole NH₃
From equation stoichiometry of balanced equation 4 moles NH₃ gives 4 moles NO. Then 0.0703 mole NH₃ => 0.0703 mole NO b/c coefficients are equal in balanced equation.
∴molecules of NO = 0.0703 mole NO x 6.03 x 10²³ molecules NO/mole NO
= 4.23 x 10²² molecules of NO.
The remaining problems can be worked much in the same way. Convert given data to moles (if not already expressed in terms of moles), apply equation ratios to calculate needed substance in moles. Finish by converting calculated moles to desired dimension.
Hints for remaining problems:
Divide given moles of reactant substances by respective coefficients, the smaller value is the limiting reactant. Work problem based on moles (not the divide value. That's just for ID of Limiting Reactant). All other reactants will be in excess.
for problem 5 ...
Given    8S(l)     +     4Cl₂(g) => 4S₂Cl₂(l)
Given:  0.433mole    0.500mole
LR Â Â Â Â 0.433/8 Â Â Â Â Â Â 0.500/4
      = 0.054       = 0.125
Limiting Reactant => Sulfur
Work problem from given 0.433 mole sulfur. Clâ‚‚ will be in excess on completion of rxn.
Summary:
- convert data to moles
- divide mole values calculated by respective coefficient => smaller value is limiting reactant.
- use mole ratios to determine results, NOT the divided by value <=> this is only for ID of limiting reactant.
If ya need more, put question in comments. I'll get it. Now, If you do need additional input, before I do I will ask if you followed the hint suggestions, and your calculation results. Good luck :-)
