🔵Kaedah melarutkn bhn kimia:

🔷melarutkn bhn kimia pepejal
guna formula:

n =MV
------
1000

*molar × JMR × Isipadu/kuantiti*

cth:NaOH..JMR 1M=40g..cth nak 5m..kuantiti 500ml/0.5liter

=5m × 40g × 0.5L
=100g

so..100g dlm 500ml air suling

🔷kaedah melarutkn bhn kimia cecair..daripada pekat kpd cair

ambil cth asid sulfurik, H2SO4
JMR/MW=98.08g/mol
% kepekatan = 98%
density/S.G = 1.84g/ml

kirakn kepekatan sebotol H2SO4

gunakn formula:

*1000*× *density* × *% kepekatan*
--------------------------------------------
*JMR*

=1000ml × 1.84 × 0.98
----------------------------------
98.08
=1803.2
-----------
98.08

=18.38 Molar

drp maklumat 18.38m..kita kira 1m pada kuantiti standard 1000ml dgn formula *M1V1=M2V2*

m1=18.38..v1=?..m2=1m..v2=1000

18.38m × v1 = 1m × 1000
v1 = 1m × 1000
----------------
18.38

= 54.4ml

so..H2SO4 1m=54.4ml dlm 1000ml air suling

*atau bole guna kaedah pengiraan* spt d bwh:

*molar × JMR* × *% Kepekatan*
--------------------
*density/S.G*

cth: H2SO4 spt d atas 👆🏾

1m × 98.08 × 100
------------------ ------
1.84 98

= 53.30434 × 1.02040
= 54.4ml dlm 1000ml air suling

🔷 formula *M1V1=M2V2* ni bole d gunakan utk mencairkan lg larutan yg da siap bancuh.

cth: H2SO4 1m...jadikn 0.1m pd kuantiti trtentu..misalnya nk kuantiti 250ml

m1=1m..v1=?..m2=0.1..v2=250ml

1m × v1 = 0.1m × 250ml
= 0.1m × 250ml
---------------------
1m

= 25ml

so..gunakn 25ml drp larutan h2so4 1m utk mbancuh h2so4 0.1m pd kuantiti 250ml..

🔷 cth:etanol 95% nk jadikan 70%..kuantiti trtentu..cth 200ml
gunakan formula:

*M1V1=M2V2*

95 × v1 = 70 × 200
= 70 × 200
-------------
95

= 147.3ml

so amik 147.3 ml drp etanol 95% jadikan 200ml..so..jadilah etanol 70%

🔷kaedah seterusnya larutan % utk larutan biologi..
*1% = 1g*

cth: kanji 10%
10% = 10g dlm 100ml air suling

🔷 bole juga d kira utk kuantiti yg lebi drp 100ml

utk mngira kuantiti bhn yg d perlukn utk larutan % melebihi 100ml..cth..250ml..500ml..1000ml & sebagainya..gunakan formula spt d bwh..

cth: pnyediaan kanji 30%..kuantiti yg cikgu perlukan 500ml.

*jisim bhn* = *Y% × V*
------------
*100*

jisim kanji = 30 × 500ml
------------------
100

=150g

so..utk mbuat larutan kanji 30% dgn kuantiti 500ml..kita perlukn 150gram kanji