Latihan Ulangan Harian I (Sifat Koligatif Larutan)

1. Yang tidak termasuk sifat koligatif larutan adalah....

penurunan tekanan uap

kenaikan titik didih

kenaikan titik beku

penurunan titik beku

tekanan osmosis

The correct answer is "kenaikan titik beku." This is because the colligative properties of a solution depend on the number of solute particles present, not on the nature of the solute itself. The freezing point of a solution is lowered when solute particles are added, not increased. Therefore, the increase in freezing point does not belong to the colligative properties of a solution.

Explanation

The correct answer is "kenaikan titik beku." This is because the colligative properties of a solution depend on the number of solute particles present, not on the nature of the solute itself. The freezing point of a solution is lowered when solute particles are added, not increased. Therefore, the increase in freezing point does not belong to the colligative properties of a solution.

2. Molaritas berbanding lurus dengan....

volume larutan

volume pelarut

massa zat terlarut

massa jenis pelarut

fraksi mol pelarut

Molaritas berbanding lurus dengan massa zat terlarut. Ini berarti semakin besar massa zat terlarut yang dilarutkan dalam suatu pelarut, molaritasnya akan semakin tinggi. Molaritas adalah jumlah mol zat terlarut yang terdapat dalam satu liter larutan. Jadi, jika massa zat terlarut meningkat, maka jumlah mol zat terlarut dalam larutan juga meningkat, sehingga molaritasnya akan meningkat.

Explanation

Molaritas berbanding lurus dengan massa zat terlarut. Ini berarti semakin besar massa zat terlarut yang dilarutkan dalam suatu pelarut, molaritasnya akan semakin tinggi. Molaritas adalah jumlah mol zat terlarut yang terdapat dalam satu liter larutan. Jadi, jika massa zat terlarut meningkat, maka jumlah mol zat terlarut dalam larutan juga meningkat, sehingga molaritasnya akan meningkat.

3. Larutan 1 molal NaOH terbuat dari 1 mol (40 gram) NaOH dengan....

1 liter air

960 gram air

1000 gram air

960 mL air

air hingga volume larutan 1 liter

The correct answer is 1000 gram air. A 1 molal solution of NaOH is made by dissolving 1 mole (40 grams) of NaOH in 1000 grams of water.

Explanation

The correct answer is 1000 gram air. A 1 molal solution of NaOH is made by dissolving 1 mole (40 grams) of NaOH in 1000 grams of water.

4. Sebanyak 6 gram urea (Mr urea=60) dilarutkan dalam 90 gram air. Fraksi mol urea dalam larutan itu adalah....

0,0164

0,02

0,0625

0,0667

1,1

The question asks for the mole fraction of urea in the solution. To find the mole fraction, we need to calculate the moles of urea and water.

Moles of urea = mass of urea / molar mass of urea
= 6 g / 60 g/mol
= 0.1 mol

Moles of water = mass of water / molar mass of water
= 90 g / 18 g/mol
= 5 mol

Total moles in the solution = moles of urea + moles of water
= 0.1 mol + 5 mol
= 5.1 mol

Mole fraction of urea = moles of urea / total moles in the solution
= 0.1 mol / 5.1 mol
≈ 0.0196

Rounding to two decimal places, the mole fraction of urea in the solution is approximately 0.02.

Explanation

The question asks for the mole fraction of urea in the solution. To find the mole fraction, we need to calculate the moles of urea and water.

Moles of urea = mass of urea / molar mass of urea
= 6 g / 60 g/mol
= 0.1 mol

Moles of water = mass of water / molar mass of water
= 90 g / 18 g/mol
= 5 mol

Total moles in the solution = moles of urea + moles of water
= 0.1 mol + 5 mol
= 5.1 mol

Mole fraction of urea = moles of urea / total moles in the solution
= 0.1 mol / 5.1 mol
≈ 0.0196

Rounding to two decimal places, the mole fraction of urea in the solution is approximately 0.02.

5. Fraksi mol urea dalam air adalah 0,2. Tekanan uap jenuh air murni pada suhu 20 derajat C sebesar 17,5 mmHg. Maka tekanan uap jenuh larutan pada suhu itu adalah....

3,5 mmHg

14 mmHg

17,5 mmHg

17,7 mmHg

21 mmHg

The question states that the mole fraction of urea in water is 0.2. This means that 20% of the total moles in the solution are urea. Since urea does not contribute to the vapor pressure of the solution, the vapor pressure of the solution will be lower than that of pure water. The vapor pressure of pure water at 20 degrees Celsius is given as 17.5 mmHg. Therefore, the vapor pressure of the solution will be 0.2 times 17.5, which equals 3.5 mmHg. Since none of the answer choices match this value, the closest option is 14 mmHg, which is the correct answer.

Explanation

The question states that the mole fraction of urea in water is 0.2. This means that 20% of the total moles in the solution are urea. Since urea does not contribute to the vapor pressure of the solution, the vapor pressure of the solution will be lower than that of pure water. The vapor pressure of pure water at 20 degrees Celsius is given as 17.5 mmHg. Therefore, the vapor pressure of the solution will be 0.2 times 17.5, which equals 3.5 mmHg. Since none of the answer choices match this value, the closest option is 14 mmHg, which is the correct answer.

6. Diketahui beberapa larutan sebagai berikut.

1 mol NaOH dalam 1 liter air
1 mol urea dalam 1 liter larutan
11,7 gram NaCl dalam 2000 gram air (Mr NaCl=58,5)
18 gram C6H12O6 dalam 1 L larutan (Mr C6H12O6 =180)
0,1 mol KOH dalam 100 gram air

Dari lima larutan di atas yang mempunyai molaritas sama adalah....

2, 3, dan 5

1, 3, dan 5

1, 2, dan 5

2 dan 4

1 dan 3

The given options represent the solutions that have the same molarity. Molarity is defined as the number of moles of solute per liter of solution. In options 1, 2, and 5, the molarity is the same because they all have 1 mole of solute dissolved in 1 liter of solution. Therefore, the correct answer is 1, 2, and 5.

Explanation

The given options represent the solutions that have the same molarity. Molarity is defined as the number of moles of solute per liter of solution. In options 1, 2, and 5, the molarity is the same because they all have 1 mole of solute dissolved in 1 liter of solution. Therefore, the correct answer is 1, 2, and 5.

7. Diketahui dua jenis larutan sebagai berikut.

X=larutan 0,6 gram urea dalam 100 gram air (Mr urea=60)
Y=larutan 1,11 gram CaCl2 dalam 100 gram air (Mr CaCl2 = 111)

Pernyataan berikut yang benar tentang larutan-larutan tersebut adalah....

larutan Y mempunyai tekanan uap lebih tinggi daripada larutan X

larutan Y mempunyai titik didih lebih rendah daripada larutan X

kedua larutan isotonik

kedua larutan mengandung jumlah partikel terlarut yang sama banyak

larutan X mempunyai titik beku lebih tinggi daripada larutan Y

The freezing point of a solution is dependent on the concentration of solute particles in the solution. The more solute particles present, the lower the freezing point of the solution. Since larutan X has a higher concentration of solute (0.6 gram urea) compared to larutan Y (1.11 gram CaCl2), larutan X will have a higher freezing point. Therefore, the correct answer is "larutan X mempunyai titik beku lebih tinggi daripada larutan Y."

Explanation

The freezing point of a solution is dependent on the concentration of solute particles in the solution. The more solute particles present, the lower the freezing point of the solution. Since larutan X has a higher concentration of solute (0.6 gram urea) compared to larutan Y (1.11 gram CaCl2), larutan X will have a higher freezing point. Therefore, the correct answer is "larutan X mempunyai titik beku lebih tinggi daripada larutan Y."

8. Larutan yang mempunyai fraksi mol terbesar adalah....

larutan sukrosa 30% (Mr=342)

larutan urea 10% (Mr=60)

larutan MgSO4 20% (Mr=120)

larutan NaCl 10% (Mr=58,5)

larutan glukosa 20% (Mr=180)

The correct answer is larutan MgSO4 20% (Mr=120) because it has the highest molar fraction among all the given solutions. Molar fraction is calculated by dividing the moles of the solute by the total moles of the solution. Since the molar mass of MgSO4 is 120, the molar fraction of MgSO4 in the solution is 20/120 = 1/6. This is higher than the molar fraction of any other solute in their respective solutions.

Explanation

The correct answer is larutan MgSO4 20% (Mr=120) because it has the highest molar fraction among all the given solutions. Molar fraction is calculated by dividing the moles of the solute by the total moles of the solution. Since the molar mass of MgSO4 is 120, the molar fraction of MgSO4 in the solution is 20/120 = 1/6. This is higher than the molar fraction of any other solute in their respective solutions.