Remed Uts Genap Xi IPA-1 Smanio (The Number Of Students Absent 21-30)

Explanation
The correct answer is CH3COOH dan HF. This is because CH3COOH (acetic acid) and HF (hydrofluoric acid) are weak acids. Weak acids are substances that do not completely ionize in water, resulting in a lower concentration of hydrogen ions (H+). HCl (hydrochloric acid) and HNO3 (nitric acid) are strong acids that completely ionize in water, producing a high concentration of H+. NH3 (ammonia) is a weak base, not an acid. Therefore, the only combination of weak acids is CH3COOH and HF.

Explanation
Red litmus paper turns blue in the presence of a base. Soap is a basic substance, so when red litmus paper is dipped in soapy water (which is a solution of soap in water), it will turn blue.

Explanation
If the ionization constant of a weak base BOH is 10^-5 M, then a 0.1 M solution of BOH will have a pH of 11. This is because the ionization constant (Ka) of a weak base is the equilibrium constant for the reaction of the base with water to produce hydroxide ions (OH-) and the conjugate acid (BH+). A higher Ka value indicates a stronger base and a higher concentration of hydroxide ions. Since the Ka value is relatively small (10^-5 M), the concentration of hydroxide ions in the solution is low, resulting in a high pH value of 11.

Explanation
When magnesium (Mg) reacts with hydrochloric acid (HCl), it produces hydrogen gas (H2) and magnesium chloride (MgCl2). 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.

Given that 4.8 grams of magnesium is reacted, we need to convert this mass to moles. The molar mass of magnesium is 24 grams/mol, so 4.8 grams is equal to 0.2 moles.

Since the ratio of magnesium to hydrogen gas in the reaction is 1:1, we can conclude that 0.2 moles of magnesium will produce 0.2 moles of hydrogen gas.

At STP (Standard Temperature and Pressure), 1 mole of any ideal gas occupies 22.4 liters. Therefore, 0.2 moles of hydrogen gas will occupy 0.2 * 22.4 = 4.48 liters.

Thus, the correct answer is 4.48 L.

Explanation
The correct answer is "penambahan banyak asam kuat." This is because a buffer solution is able to maintain its pH within a certain range by resisting changes in pH when small amounts of acid or base are added. However, if a large amount of strong acid is added to the buffer solution, it will overpower the buffer capacity and cause a significant change in pH. Therefore, the addition of a large amount of strong acid disrupts the ability of the buffer solution to maintain its pH.

Explanation
The given question states that 25 mL of 0.2 M CH3COOH (acetic acid) is mixed with 25 mL of 0.1 M NaOH (sodium hydroxide) to form a buffer solution. Acetic acid is a weak acid with a Ka value of 10^-5 M. When acetic acid reacts with sodium hydroxide, it forms sodium acetate (CH3COONa) and water. The acetic acid and its conjugate base, acetate, act as a buffer system in the solution. The pH of a buffer solution is determined by the ratio of the concentrations of the weak acid and its conjugate base. In this case, the ratio of acetic acid to acetate is 1:1, resulting in a pH of 5.0, which is the correct answer.

Explanation
KCN is the correct answer because it is a salt that is formed from a strong base (KOH) and a weak acid (HCN). When KCN is dissolved in water, it undergoes hydrolysis to produce OH- ions, which makes the solution basic. This is because the weak acid, HCN, partially dissociates in water to form H+ ions and CN- ions. The CN- ions react with water to form OH- ions, increasing the concentration of OH- ions and making the solution basic.

Explanation
Amonium asetat mengalami hidrolisis sempurna jika dilarutkan ke dalam air. Hidrolisis adalah reaksi kimia di mana senyawa terurai menjadi dua atau lebih senyawa baru karena reaksi dengan air. Dalam kasus amonium asetat, reaksi hidrolisisnya menghasilkan ion asetat (CH3COO-) dan ion amonium (NH4+). Kedua ion ini terbentuk karena gugus amonium (NH4+) dalam amonium asetat melepaskan satu ion H+ ke dalam air, sehingga membentuk ion amonium, sementara gugus asetat (CH3COO-) membentuk ion asetat. Karena reaksi ini terjadi secara sempurna, amonium asetat dapat dianggap mengalami hidrolisis sempurna.

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. In this case, the solution is made of NH3, which is ammonia. Ammonia is a weak base that ionizes to produce hydroxide ions (OH-) in water. The higher the concentration of hydroxide ions, the higher the pH. Therefore, a solution of NH4Cl, which is the conjugate acid of NH3, would have a lower pH than 11. Among the given options, a pH of 5 is the closest to being lower than 11, making it the correct answer.

Explanation
Campuran larutan 50 mL 0,5 M CH3COOH + 50 mL 0,5 M NaOH menghasilkan garam terhidrolisis sebagian dan bersifat basa karena CH3COOH adalah asam lemah dan NaOH adalah basa kuat. Ketika kedua larutan dicampur, CH3COOH akan bereaksi dengan NaOH membentuk garam CH3COONa dan air. Garam CH3COONa adalah garam yang terhidrolisis sebagian, artinya akan ada ion OH- yang terhidrolisis. Ion OH- yang terhidrolisis akan meningkatkan konsentrasi OH- dalam larutan, sehingga larutan bersifat basa.