Name: strong acids, strong bases, and ph
Uploaded: 2020-09-24T15:06:51.000Z
Duration: 3 min 22 s
Channel: JoVE

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Strong Acid and Base Solutions

강한 산은 물에서 완전히 해리됩니다. 예를 들어 질산은 하이드로늄 이온과 질산 이온으로 완전히 해리됩니다. 물의 자동 이온화에서 발생하는 하이드로늄 이온은 무시할 수 있는 정도이기 때문에 물 속의 하이드로늄 이온의 농도는 강산의 농도와 같습니다.

이러한 용액의 pH는 강산의 초기 농도를 사용하여 결정할 수 있습니다. 예를 들어 0.10 몰의 HCl 용액에서 HCl은 하이드로늄 이온과 염화 이온으로 완전히 해리되므로 용액의 하이드로늄 이온 농도도 0.10 몰이 됩니다. 이 농도에 마이너스 로그를 취하면 용액의 pH는 1과 같습니다.

반대로, 용액의 pH는 용액의 하이드로늄 이온 농도를 결정하는 데 사용될 수 있습니다. 예를 들어 pH가 3.60인 용액의 경우 용액의 하이드로늄 이온 농도는 3.60이 하이드로늄 이온 농도의 마이너스 로그와 같게 되는 방정식을 풀어서 결정할 수 있습니다. 농도를 풀기 위해 양쪽에 음수를 곱한 다음 양쪽에 역대수를 취합니다.

하이드로늄 이온 농도는 2.5 10⁻⁴ 몰과 같습니다. 수산화나트륨과 수산화칼륨과 같은 하나의 금속으로 이루어진 강염기는 용액으로 완전히 해리됩니다. 예를 들어 수산화나트륨 0.20 몰은 물에서 완전히 해리되어 나트륨 이온 0.20 몰과 수산화 이온 0.20 몰을 생성합니다.

그러나 수산화 바륨과 수산화칼슘과 같은 두 개의 금속 수산화물은 각각의 염기 한 몰에 대해 두 몰의 수산화이온을 생성합니다. 예를 들어 수산화칼슘 0.020 몰은 물에서 완전히 해리되어 0.020 몰의 칼슘 이온과 0.040 몰의 수산화 이온을 생성합니다. 산화나트륨과 산화칼슘과 같은 이온 금속 산화물 또한 강염기입니다.

그것들의 산화 이온은 물과 반응하여 수산화 이온을 생성합니다. 수산화 이온의 농도를 이용하여 용액의 pOH와 pH를 계산할 수 있습니다. 예를 들어 5 10⁻⁵ 몰의 수산화 칼륨 용액은 강 염기인 수산화 이온과 같은 량을 가지며 따라서 pOH는 4.30입니다.

pH와 마찬가지로 용액의 pOH을 사용하여 다음 방정식을 풀어 수산화 이온 농도를 결정할 수 있으며 pOH는 수산화 이온 농도의 마이너스 로그와 같습니다. pH 플러스 pOH는 14이고 pOH는 4.3이므로 용액의 pH는 9.7입니다.

강산 및 염기 용액

강산은 수용액에서 완전히 해리되어 산의 초기 농도와 동일한 농도의 하이드로늄 이온을 생성하는 화합물입니다. 예를 들어, 0.20M 브롬화수소산은 물에서 완전히 해리되어 0.20M 하이드로늄 이온과 0.20M 브롬화물 이온을 생성합니다.

<img alt="Eq1" src="/files/ftp_upload/11399/11399_Equation_1.png" style="height: 50px;" />

반면, 강염기는 수용액에서 완전히 해리되어 수산화물 이온을 생성하는 화합물입니다. 예를 들어, 1족 금속 수산화물인 0.015M KOH는 완전히 해리되어 0.015M의 OH^-와 0.015M의 K^+를 생성합니다.

<img alt="Eq2" src="/files/ftp_upload/11399/11399_Equation_2.png" style="height: 50px;" />

수산화바륨[Ba(OH)_2] 및 수산화스트론튬[Sr(OH)_2]과 같은 2족 금속 수산화물도 강염기이며 두 개의 수산화물 이온을 가지고 있습니다. 이로 인해 동일한 농도의 NaOH 또는 KOH에 비해 더 기본적인 용액이 생성됩니다. 예를 들어, 0.015M Ba(OH)_2는 0.015M Ba^+와 0.030M 수산화물을 생성합니다.

<img alt="Eq3" src="/files/ftp_upload/11399/11399_Equation_3.png" style="height: 50px;" />

강산과 강염기가 완전히 해리되면 몰비를 사용하여 수소 및 수산화물 농도를 결정할 수 있으며, 이는 다시 용액의 pH 또는 pOH를 계산하는 데 사용할 수 있습니다. 예를 들어, 0.030M HCl 용액은 0.03M 하이드로늄 이온을 생성합니다. 따라서 이 용액의 pH는

<img alt="Eq4" src="/files/ftp_upload/11399/11399_Equation_4.png" style="height: 135px;" />

동일한 용액의 pOH는 다음 공식을 사용하여 결정할 수 있습니다.

<img alt="Eq5" src="/files/ftp_upload/11399/11399_Equation_5.png" style="height: 50px;" />

용액의 pH가 1.52이므로 pOH는 다음과 같이 계산할 수 있습니다.

<img alt="Eq6" src="/files/ftp_upload/11399/11399_Equation_6.png" style="height: 50px;" />

마찬가지로, 강염기에 의해 생성된 수산화 이온의 농도는 다음 방정식을 사용하여 용액의 pOH를 결정하는 데 사용될 수 있습니다.

<img alt="Eq7" src="/files/ftp_upload/11399/11399_Equation_7.png" style="height: 50px;" />

위의 방정식은 pOH가 알려진 경우 수산화물 이온 농도를 결정하는 데에도 사용할 수 있습니다. 예를 들어 용액의 pOH가 3.00이라면,

<img alt="Eq8" src="/files/ftp_upload/11399/11399_Equation_8.png" style="height: 50px;" />

양변에 −1을 곱하면 다음과 같습니다.

<img alt="Eq9" src="/files/ftp_upload/11399/11399_Equation_9.png" style="height: 50px;" />

이제 양변의 역대수를 취하세요.

<img alt="Eq10" src="/files/ftp_upload/11399/11399_Equation_10.png" style="height: 90px;" />

따라서 pOH 3을 갖는 용액의 히드로늄 이온 농도는 1.0 x 10^-3 M입니다. pH가 알려진 경우 용액의 히드로늄 이온 농도를 결정하는 데 유사한 방법을 사용할 수 있습니다.

강산은 수용액에서 완전히 해리되고 초기와 동일한 히드로늄 이온의 농도를 생성하는 화합물입니다.

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Acids and Bases

산과 염기

KEY TERMS AND CONCEPTS

주요 용어 및 개념

strong acids, strong bases, and ph

Strong acids and strong bases change the pH of a solution by dissociating completely in water. A strong acid produces hydronium ions, which are H3O+ ions, and a strong base produces hydroxide ions, OH-. Because the dissociation is complete, the ion concentration can be found from the starting concentration and the molar ratio.

For example, 0.20 M hydrobromic acid dissociates fully in water. It produces 0.20 M hydronium ions and 0.20 M bromide ions. A 0.015 M KOH solution also dissociates completely. It produces 0.015 M OH- and 0.015 M K+.

Some group 2 metal hydroxides are also strong bases. Barium hydroxide, Ba(OH)2, and strontium hydroxide, Sr(OH)2, each contain two hydroxide ions. That means they create a more basic solution than NaOH or KOH at the same concentration. For example, 0.015 M Ba(OH)2 produces 0.015 M Ba+ and 0.030 M hydroxide.

The ion concentrations from strong acids and strong bases can be used to calculate pH and pOH. A 0.030 M HCl solution produces 0.03 M hydronium ions, so its pH can be found from that concentration. The same pH value can then be used to determine pOH. If the pH is 1.52, the pOH can be calculated from the relationship between them.

The same idea works for strong bases. The hydroxide ion concentration can be used to find pOH with the equation for pOH, and the equation can also be used in reverse when pOH is known. For example, if the pOH of a solution is 3.00, multiplying by -1 and taking the antilog gives a hydronium ion concentration of 1.0 × 10^-3 M. The same method can be used to find hydronium ion concentration when pH is known.

Strong Acids, Strong Bases, and pH

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Acids and bases can be understood through proton transfer. Early scientists described acids by their sour taste, their effect on dyes, and their reaction with limestone, which releases carbon dioxide. Robert Boyle also noted that acid solutions can lose these properties after contact with alkali, or base, solutions. The modern view developed step by step. Humphry Davy showed that hydrogen is the essential part of acids. Joseph Louis Gay-Lussac then described acids as substances that neutralize...

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How Ka and Kb Show Acid-Base Strength

Brønsted-Lowry acid-base chemistry is based on proton transfer. That idea helps show how the strength of an acid is linked to the strength of its conjugate base, and vice versa. Acid and base strength is measured with ionization constants, Ka and Kb, which tell how far an ionization reaction goes. For the conjugate pair HA and A−, the acid ionizes in water and the base reaction can be written for the partner species. When the two reactions are added, they give the autoionization of water. The...

strong acid and base solutions

Strong acids and strong bases change the pH of a solution by dissociating completely in water. A strong acid produces hydronium ions, which are H3O+ ions, and a strong base produces hydroxide ions, OH-. Because the dissociation is complete, the ion concentration can be found from the starting concentration and the molar ratio. For example, 0.20 M hydrobromic acid dissociates fully in water. It produces 0.20 M hydronium ions and 0.20 M bromide ions. A 0.015 M KOH solution also dissociates...

weak acid solutions

Weak Acid Equilibrium in Water

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weak base solutions

Weak Base pH and Kb Calculations

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mixtures of acids

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acid/base strengths and dissociation constants

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key terms and concepts

Learn how strong acids and strong bases dissociate completely in water and how their ion concentrations are used to calculate pH and pOH.

Strong Acids, Strong Bases, and pH | JoVE K12

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Construct an explanation to summarize the influences intermolecular forces have on the properties of chemical compounds.

PS.Chm.3.2

Analyze the structure of atoms and isotopes.

Strong Acids, Strong Bases, and pH

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