Help me find ? please 1) 3 Pb(NO3)2(aq) + 2 Na3PO4(aq) 1 Pb3(PO4)2(s) + 6 NaNO3(

Question

Help me find ? please

1)

3 Pb(NO3)2(aq) + 2 Na3PO4(aq) 1 Pb3(PO4)2(s) + 6 NaNO3(aq)

Initial moles Pb(NO3)2 = 1.5×10-4 mol (1.5mL, 0.1M)

Initial moles Na3PO4 = 7.5×10-5 mol (0.25mL, 0.3M)

Number of moles of Pb3(PO4)2 that can be formed from each starting reagent is:

1-1. from Pb(NO3)2 = ? mol Pb3(PO4)2

1-2. from Na3PO4 = ? mol Pb3(PO4)2

1-3. Give the chemical formula for the starting solution that was the limiting reagent?   

2)

3 Co(NO3)2(aq)(aq) + 2 Na3PO4(aq) 1 Co3(PO4)2(s) + 6 NaNO3(aq)

Initial moles Co(NO3)2 = 5.0×10-5 mol (0.5mL, 0.1M)

Initial moles Na3PO4 = 3.0×10-4 mol (1mL, 0.3M)

Number of moles of Co3(PO4)2 that can be formed from each starting reagent is:

2-1. from Co(NO3)2 = ?   mol Co3(PO4)2

2-2. from Na3PO4 = ? mol Co3(PO4)2

2-3. Give the chemical formula for the starting solution that was the limiting reagent?

Explanation / Answer

1) 3 Pb(NO3)2(aq) + 2 Na3PO4(aq) 1 Pb3(PO4)2(s) + 6 NaNO3(aq)

1-1) We stablish stechiometric relations with the equation

3 Pb(NO3)2 -------produces------ 1moles Pb3(PO4)2

1,5*10^-4moles ----------------------X

X= 2,5*10^-5moles  Pb3(PO4)2

1-2) We stablish stechiometric relations with the equation

2moles of Na3PO4 -------produces------- 1mol of Pb3(PO4)2

7,5*10^-5mol ------------------------------------X

X= 3,8*10-5 moles of Pb3(PO4)2

1-3) 3 mole of  Pb(NO3)2 --------------------2 moles of Na3PO4

X ----------------------------------------------- 7,5*10^-5 moles of Na3PO4

X= 1,1*10^-4 moles of Pb(NO3)2

In the excercise they are telling us that we added 1,5*10^-5moles of Pb(NO3)2 so this is the reactant in exces and the Na3PO4 is the limitant reagent.

2) 2-1) 3moles Co(NO3)2 --------produces------ 1mol Co3(PO4)2

5,0*10^-5 mol -------------------------------- X

X= 1,7*10^-5 moles of Co3(PO4)2

2-2) 2 moles of Na3PO4 ------------- 1mol Co3(PO4)2

3,0*10^-4moles -------------------- X

X= 1,5*10^-4moles of Co3(PO4)2

2-3) 3moles of Co(NO3)2 --------reacts-------- 2moles of Na3PO4(aq)

5,0*10^-5moles --------------------------------- X

X= 3,3*10^-5moles of Na3PO4

So we need 3,3*10^-5moles of Na3PO4 to react completly with 5,0*10^-5moles of Co(NO3)2 and we are adding 3.0×10-4 mol so the limitant reagent is Co(NO3)2

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