4.2.2 Perhitungan Kadar Amonia NH
3
Pembuatan larutan induk
-1000 ppm
MgL NH
4
Cl = x V
= x 1000 mgL
= 3,817 gL
Pembuatan larutan standar
-100 ppm -10 ppm
V
1
. N
1
= V
2
. N
2
V
1
. N
1
= V
2
. N
2
V
1
. 1000 = 100 . 100 V
1
. 100 = 250 . 10 V
1
= 10 ml V
1
= 25 ml
Pembuatan larutan seri standard
-0,0 ppm -1,5 ppm
V
1
. N
1
= V
2
. N
2
V
1
. N
1
= V
2
. N
2
V
1
. 10 = 100 . 0,0 V
1
. 10 = 100 . 1,5 V
1
= 0ml V
1
= 15 ml
-0,5 ppm -2,0 ppm
V
1
. N
1
= V
2
. N
2
V
1
. N
1
= V
2
. N
2
V
1
. 10 = 100 . 0,5 V
1
. 10 = 100 . 2,0 V
1
= 5 ml V
1
= 20 ml Mr
BA
53,45 14
-1,0 ppm -2,5 ppm
V
1
. N
1
= V
2
. N
2
V
1
. N
1
= V
2
. N
2
V
1
. 10 = 100 . 1 V
1
. 10 = 100 . 2,5 V
1
= 10 ml V
1
= 25 ml
Perhitungan metode least square
Tabel 4.2.2.1. Data perhitungan persamaan garis regresi untuk analisis amonia NH
3
dengan spektrofotometer UV-Vis
No x
Y xy
x
2
1 0,0
0,000 0,000
2 0,5
0,202 0,101
0,25 3
1,0 0,407
0,407 1
4 1,5
0,600 0,9
2,25 5
2,0 0,812
1,624 4
6 2,5
1,133 2,8325
6,25 ∑ x = 7,5
∑ y = 3,154 ∑xy = 5,8645
∑ x² = 13,75
a =
=
=
=
= n Σxy - ΣxΣy
n Σ - Σx
65,864 - 7,53,154 613,75 – 7,5
35,184 – 23,655 82,5 – 56,25
11,529 26,25
0,4392
b =
=
=
=
=
Y = ax + b Y1 = 0,4392 0,0 + -0,0236 = -0,0236
Y2 = 0,4392 0,5 + -0,0236 = 0,196 Y3 = 0,4392 1,0 + -0,0236 = 0,4156
Y4 = 0,4392 1,5 + -0,0236 = 0,6352 Y5 = 0,4392 2,0 + -0,0236 = 0,8548
Y6 = 0,4392 2,5 + -0,0236 = 1,0744
Tabel 4.2.2.2. Harga Y baru untuk larutan standart amonia NH
3
X Y
0,0 -0,0236
0,5 0,196
1,0 0,4156
1,5 0,6352
2,0 0,8548
2,5 1,0744
Σ Σy – ΣxΣy n Σ – Σx
13,753,154- 7,55,864 6 13,75 - 7,5
43,36 – 43,98 82,5 – 56,25
-0,62 26,25
-0,0236
Perhitungan untuk sampel amonia Y = ax + b
X =
• Air sungai Biru-biru
X
1
=
= 0,101
X
2
=
= 0,108
X
3
=
= 0,114
• Air sungai Sembahe
X
1
=
= 0,087
Y – b a
0,021 – -0,0234 0,4392
0,024 – -0,0234 0,4392
0,027 – -0,0234 0,4392
0,015 – -0,0234 0,4392
X
2
=
= 0,0988
X
3
=
= 0,110
• Air sungai Juanda
X
1
=
= 2,054
X
2
=
= 2,104
X
3
=
= 2,157
0,02 – -0,0234 0,4392
0,025 – -0,0234 0,4392
0,879 – -0,0234 0,4392
0,901 – -0,0234 0,4392
0,924 – -0,0234 0,4392
• Air sungai Pertempuran
X
1
=
= 2,633
X
2
=
= 2,655
X
3
=
= 2,680
1,133 – -0,0234 0,4329
1,143 – -0,0234 0,4329
1,154 – -0,0234 0,4329
4.3. Pembahasan
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