Limiting Reactant Notes Scroggs Spring 2020 Limiting vs

Limiting Reactant Notes Scroggs Spring 2020

Limiting vs. Excess http: //www. youtube. com/watch? v=o. YIHLUxz. Rr 8

Limiting vs. Excess • Limiting reagent – The first reactant used up in a reaction – After it’s gone, no more product formed – “A” part will be zero

Limiting vs. Excess • Excess reagent – Not used up in a reaction, extra left over – “A” part will have a positive number

Calculating Limiting Reagent • • Write balanced equation Fill in each reactant in the BCA table “B” part Fill in the “C” part of BCA Set ONE reactant to 0; solve for x (usually pick the reactant that is the smaller number) – After solve for “x”, plug value into the other reactant • If you have something leftover, good • If you have negative moles leftover, bad (erase and set this reactant to 0 and start over solving for x) – The reactant that is 0 in “A” part, is limiting reactant (LR) – The reactant that has a number in “A” part, is excess reactant (EX) • Once you solved for “x” correctly, you can solve for the product value they are asking about – Usually need answer in grams

Ex 1. Given 5. 0 grams of KOH and 2. 0 grams of H 3 PO 4, how much (grams) of K 3 PO 4 can be prepared? H 3 PO 4 + 3 KOH K 3 PO 4 + 3 H 2 O

Ex 2. Given 16 grams of KOH and 22 grams of H 3 PO 4, how much (grams) of K 3 PO 4 can be prepared? How much(g) excess reactant remains? H 3 PO 4 + 3 KOH K 3 PO 4 + 3 H 2 O