Remed Uts Genap Xi IPA-2 Smanio (The Number Of Students Absent 21-30)

1. Sebanyak 4,8 gram logam Mg(Ar = 24) direaksikan dengan larutan HCl 1 M. Jika semua logam Mg habis bereaksi, maka volume gas hidrogen yang terjadi (pada keadaan STP) adalah ...

2,24 L

4,48 L

5,60 L

11,20 L

22,4

When magnesium (Mg) reacts with hydrochloric acid (HCl), it produces magnesium chloride (MgCl2) and hydrogen gas (H2). The balanced chemical equation for this reaction is:

Mg + 2HCl → MgCl2 + H2

From the equation, we can see that 1 mole of magnesium reacts with 2 moles of hydrochloric acid to produce 1 mole of hydrogen gas. The molar mass of Mg is 24 g/mol, so 4.8 grams of Mg is equal to 0.2 moles.

Since the reaction is at STP (Standard Temperature and Pressure), 1 mole of any gas occupies 22.4 liters. Therefore, 0.2 moles of hydrogen gas will occupy 0.2 * 22.4 = 4.48 liters. Hence, the volume of hydrogen gas produced in this reaction is 4.48 L.

Explanation

When magnesium (Mg) reacts with hydrochloric acid (HCl), it produces magnesium chloride (MgCl2) and hydrogen gas (H2). The balanced chemical equation for this reaction is:

Mg + 2HCl → MgCl2 + H2

From the equation, we can see that 1 mole of magnesium reacts with 2 moles of hydrochloric acid to produce 1 mole of hydrogen gas. The molar mass of Mg is 24 g/mol, so 4.8 grams of Mg is equal to 0.2 moles.

Since the reaction is at STP (Standard Temperature and Pressure), 1 mole of any gas occupies 22.4 liters. Therefore, 0.2 moles of hydrogen gas will occupy 0.2 * 22.4 = 4.48 liters. Hence, the volume of hydrogen gas produced in this reaction is 4.48 L.

2.

1

2

3

4

5

not-available-via-ai

Explanation

not-available-via-ai

3. Dari contoh larutan di bawah ini yang termasuk larutan asam lemah adalah….

NH3 dan HCN

NaOH dan HCN

CO(NH2)2 dan NH3

CH3COOH dan CO(NH2)2

CH3COOH dan HCN

The correct answer is CH3COOH dan HCN. CH3COOH is acetic acid, which is a weak acid. HCN is hydrocyanic acid, which is also a weak acid. Weak acids are substances that partially dissociate in water, releasing a small amount of hydrogen ions (H+). In this case, both CH3COOH and HCN will only release a small amount of H+ ions when dissolved in water, making them weak acids.

Explanation

The correct answer is CH3COOH dan HCN. CH3COOH is acetic acid, which is a weak acid. HCN is hydrocyanic acid, which is also a weak acid. Weak acids are substances that partially dissociate in water, releasing a small amount of hydrogen ions (H+). In this case, both CH3COOH and HCN will only release a small amount of H+ ions when dissolved in water, making them weak acids.

4. Campuran yang dapat membentuk larutan penyangga adalah .…

50 mL CH3COOH 0,2 M + 50 mL NaOH 0,1 M

50 mL HCl 0,2 M + 100 mL NH3 0,1 M

50 mL HCl 0,2 M + 50 mL NH3 0,1 M

50 mL CH3COOH 0,2 M + 100 mL NaOH 0,1 M

50 mL HCl 0,2 M + 50 mL NaOH 0,1 M

The given answer of "50 mL CH3COOH 0,2 M + 50 mL NaOH 0,1 M" is correct because it consists of a weak acid (CH3COOH) and its conjugate base (CH3COO-) provided by the NaOH. This combination forms a buffer solution, which can resist changes in pH when small amounts of acid or base are added. The equal volumes of the acid and base ensure that the buffer is at its optimal capacity.

Explanation

The given answer of "50 mL CH3COOH 0,2 M + 50 mL NaOH 0,1 M" is correct because it consists of a weak acid (CH3COOH) and its conjugate base (CH3COO-) provided by the NaOH. This combination forms a buffer solution, which can resist changes in pH when small amounts of acid or base are added. The equal volumes of the acid and base ensure that the buffer is at its optimal capacity.

5. Suatu zat dapat digunakan sebagai indikatorasam basa, jika zat tersebut ….

Dapat bereaksi dengan asam atau basa

Dapat terionisasi dalam larutan

Dapat memberikan warna yang berbeda dalam lingkungan asam danbasa

Dapat memberikan warna tertentu dalam asam tetapi tidak berwarna dalambasa

Memberikan warna yang sama dalam lingkungan asam dan basa

A substance can be used as an acid-base indicator if it is able to give different colors in acidic and basic environments.

Explanation

A substance can be used as an acid-base indicator if it is able to give different colors in acidic and basic environments.

6. Sebanyak 25 mL CH3COOH 0,2 M (Ka = 10–5 M) dicampurkan dengan 25 mL NaOH 0,1 M membentuk larutan penyangga dengan pH ....

2,0

2,5

3,0

5,0

5,5

The correct answer is 5.0. When acetic acid (CH3COOH) reacts with sodium hydroxide (NaOH), they undergo a neutralization reaction to form sodium acetate (CH3COONa) and water (H2O). Sodium acetate is a salt that acts as a weak base in solution. The reaction between CH3COOH and NaOH consumes equal moles of each compound, resulting in a solution with equal concentrations of the conjugate acid-base pair. The pH of a buffer solution is determined by the pKa of the weak acid and the ratio of the concentrations of the acid and its conjugate base. In this case, the pKa of acetic acid is 5, so the pH of the buffer solution will be approximately 5.0.

Explanation

The correct answer is 5.0. When acetic acid (CH3COOH) reacts with sodium hydroxide (NaOH), they undergo a neutralization reaction to form sodium acetate (CH3COONa) and water (H2O). Sodium acetate is a salt that acts as a weak base in solution. The reaction between CH3COOH and NaOH consumes equal moles of each compound, resulting in a solution with equal concentrations of the conjugate acid-base pair. The pH of a buffer solution is determined by the pKa of the weak acid and the ratio of the concentrations of the acid and its conjugate base. In this case, the pKa of acetic acid is 5, so the pH of the buffer solution will be approximately 5.0.

7. Larutan garam yang dapat memerahkan kertas lakmus adalah .…

Na2SO4 (aq)

KCl (aq)

HCOONa (aq)

NaNO3 (aq)

(NH4)2SO4 (aq)

The correct answer is (NH4)2SO4 (aq). Ammonium sulfate is a salt that can dissociate into ammonium ions (NH4+) and sulfate ions (SO4^2-). When dissolved in water, the ammonium ions can react with the water molecules to form hydronium ions (H3O+), which can turn the blue litmus paper red. Therefore, (NH4)2SO4 (aq) is the correct answer.

Explanation

The correct answer is (NH4)2SO4 (aq). Ammonium sulfate is a salt that can dissociate into ammonium ions (NH4+) and sulfate ions (SO4^2-). When dissolved in water, the ammonium ions can react with the water molecules to form hydronium ions (H3O+), which can turn the blue litmus paper red. Therefore, (NH4)2SO4 (aq) is the correct answer.

8. Asam lemah HA 0,1 M terurai dalam air sebanyak 2%. Tetapan ionisasi asam lemah tersebut adalah ….

2 × 10–3

4 × 10–4

4 × 10–3

4 ×10–5

. 2 × 10–4

The given question is asking for the ionization constant of a weak acid, which is represented by the symbol Ka. The information provided states that a 0.1 M weak acid solution is 2% ionized in water. This means that only 2% of the weak acid molecules dissociate into ions in the solution. The ionization constant, Ka, is calculated by dividing the concentration of the products (H+ ions and the conjugate base) by the concentration of the weak acid. Since only 2% of the weak acid is ionized, the concentration of the products is 2% of 0.1 M, which is 0.002 M. Dividing 0.002 M by 0.1 M gives a value of 0.02, which is equivalent to 4 × 10–5. Therefore, the correct answer is 4 × 10–5.

Explanation

The given question is asking for the ionization constant of a weak acid, which is represented by the symbol Ka. The information provided states that a 0.1 M weak acid solution is 2% ionized in water. This means that only 2% of the weak acid molecules dissociate into ions in the solution. The ionization constant, Ka, is calculated by dividing the concentration of the products (H+ ions and the conjugate base) by the concentration of the weak acid. Since only 2% of the weak acid is ionized, the concentration of the products is 2% of 0.1 M, which is 0.002 M. Dividing 0.002 M by 0.1 M gives a value of 0.02, which is equivalent to 4 × 10–5. Therefore, the correct answer is 4 × 10–5.

9. Dari campuran larutan berikut yang menghasilkan garam terhidrolisis sebagian dan bersifat basa adalah ....

50 mL 0,5 M HCl + 50 mL 0,5 MNaOH

50 mL 0,5 M HCl + 50 mL 0,5 MNH3

50 mL 0,5 M HCl + 100 mL 0,5 MNH3

50 mL 0,5 M CH3COOH + 50 mL 0,5M NH3

50 mL 0,5 M CH3COOH + 50 mL0,5 M NaOH

The correct answer is 50 mL 0,5 M CH3COOH + 50 mL 0,5 M NaOH. This is because acetic acid (CH3COOH) and sodium hydroxide (NaOH) react to form sodium acetate (CH3COONa) and water (H2O). Sodium acetate is a salt that undergoes partial hydrolysis in water, resulting in the release of hydroxide ions (OH-) and making the solution basic.

Explanation

The correct answer is 50 mL 0,5 M CH3COOH + 50 mL 0,5 M NaOH. This is because acetic acid (CH3COOH) and sodium hydroxide (NaOH) react to form sodium acetate (CH3COONa) and water (H2O). Sodium acetate is a salt that undergoes partial hydrolysis in water, resulting in the release of hydroxide ions (OH-) and making the solution basic.

10. Larutan NH3 0,1 M mempunyai pH = 11, pH larutan NH4Cl 0,1 M adalah ….

11

9

7

5

3

The pH of a solution is a measure of its acidity or alkalinity. A pH of 11 indicates that the solution is highly alkaline. When NH3 (ammonia) dissolves in water, it forms NH4+ (ammonium) and OH- (hydroxide) ions. The NH4Cl solution is formed by dissolving NH4Cl (ammonium chloride) in water. Ammonium chloride is a salt that dissociates into NH4+ and Cl- ions in water. Since NH4+ is the conjugate acid of NH3, it can react with water to release H+ ions, making the solution acidic. Therefore, the pH of the NH4Cl solution will be lower than the pH of the NH3 solution. Among the given options, a pH of 5 is the closest to being acidic.

Explanation

The pH of a solution is a measure of its acidity or alkalinity. A pH of 11 indicates that the solution is highly alkaline. When NH3 (ammonia) dissolves in water, it forms NH4+ (ammonium) and OH- (hydroxide) ions. The NH4Cl solution is formed by dissolving NH4Cl (ammonium chloride) in water. Ammonium chloride is a salt that dissociates into NH4+ and Cl- ions in water. Since NH4+ is the conjugate acid of NH3, it can react with water to release H+ ions, making the solution acidic. Therefore, the pH of the NH4Cl solution will be lower than the pH of the NH3 solution. Among the given options, a pH of 5 is the closest to being acidic.