A standard solution was prepared by combining the solutions given below and then

Question

A standard solution was prepared by combining the solutions given below and then diluting to a total volume of 25.00 mL with deionized water. What is the concentration (in M) of FeSCN2+ in the standard solution? Assume that all of the Fe3+ reacts with SCN? to produce FeSCN2+.

10.00 mL 0.00200 M Fe(NO3)3

6.00 mL 0.00200 M KSCN

2.50 mL 0.10 M HNO3

A standard solution was prepared bv combining the solutions given below and then diluting to a total volume of 25.00 mL with deionized water. What is the concentration (in M) of FeSCN2+ in the standard solution? Assume that all of the Fe* reacts with SCN to produce FeSCN2+ 2+ 10.00 mL 0.00200 M Fe(NO3)3 6.00 mL 0.00200 M KSCN 2.50 mL 0.10 M HNO3 (a) 1.20 x 105 M (b) 2.00 x 104 M (c) 4.80 x 104 M (d) 6.49 x 104 M (e) 8.00 x 104 M

Explanation / Answer

we know that

moles = concentration x volume (ml) / 1000

so

moles of Fe+3 = 0.002 x 10 / 1000 = 2 x 10-5

moles of SCN- = 0.002 x 6 / 1000 = 1.2 x 10-5

now

the reaction is given by

Fe+3 + SCN- = FeSCN+2

now

we can see that

moles of Fe+3 reacted = moles of SCN- present = 1.2 x 10-5

but

2 x 10-5 moles of Fe+3 is present

so

Fe+3 is in excess and SCN- is the limiting reagent

now

moles of FeSCN+2 formed = moles of Fe+3 reacted = 1.2 x 10-5

now

final volume = 10 + 6 + 2.5 = 18.5 ml

so

concentration of FeSCN+2 = moles x 1000/ volume (ml)

= 1.2 x 10-5 x 1000 / 18.5

= 6.49 x 10-4

so

concentration of FeSCN+2 is 6.49 x 10-4 M

so

the answer is option d) 6.49 x 10-4 M

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.