The capacity of batteries such as the typical AA alkaline battery is expressed in units of milliamp-hours (mAh). An AA alkaline battery yields a nominal capacity of 2850 mAh. (a) What quantity of interest to the consumer is being expressed by the units of mAh?

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780134414232

검증된 단계별 안내

The unit milliamp-hours (mAh) is a measure of electric charge. It indicates the total amount of electric charge a battery can deliver over time.

To understand mAh, consider that 1 milliamp-hour is the amount of charge transferred by a current of 1 milliampere flowing for 1 hour.

In the context of a battery, mAh represents the battery's capacity to deliver a certain current over a specified period. For example, a 2850 mAh battery can theoretically deliver 2850 milliamperes for 1 hour, or 1 milliampere for 2850 hours.

This measure is important to consumers because it gives an indication of how long a battery will last under a specific load or usage condition.

Therefore, the quantity of interest to the consumer expressed by mAh is the battery's capacity or the total charge it can provide before needing to be recharged or replaced.

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Electric Charge

Electric charge is a fundamental property of matter that causes it to experience a force when placed in an electromagnetic field. In the context of batteries, charge is measured in coulombs, and milliamp-hours (mAh) is a unit that quantifies the total charge a battery can deliver over time. Understanding electric charge is essential for interpreting battery capacity.

Current

Current is the flow of electric charge, measured in amperes (A). In the case of milliamp-hours, the 'milli' prefix indicates that the current is measured in milliamperes (mA), which is one-thousandth of an ampere. The relationship between current, time, and charge is crucial for consumers to understand how long a battery can power a device before needing replacement.

Battery Capacity

Battery capacity refers to the total amount of electric charge a battery can store and deliver, typically expressed in milliamp-hours (mAh). This measurement indicates how long a battery can provide a specific current before it is depleted. For consumers, a higher mAh rating generally means longer usage time for devices powered by the battery.

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교과서 질문

The capacity of batteries such as the typical AA alkaline battery is expressed in units of milliamp-hours (mAh). An AA alkaline battery yields a nominal capacity of 2850 mAh. (b) The starting voltage of a fresh alkaline battery is 1.55 V. The voltage decreases during discharge and is 0.80 V when the battery has delivered its rated capacity. If we assume that the voltage declines linearly as current is withdrawn, estimate the total maximum electrical work the battery could perform during discharge.

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교과서 질문

Disulfides are compounds that have S ¬ S bonds, like peroxides have O ¬ O bonds. Thiols are organic compounds that have the general formula R ¬ SH, where R is a generic hydrocarbon. The SH- ion is the sulfur counterpart of hydroxide, OH-. Two thiols can react to make a disulfide, R ¬ S ¬ S ¬ R. (b) What is the oxidation state of sulfur in a disulfide?

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교과서 질문

(b) Given the following reduction potentials, calculate the standard emf of the cell: Cd1OH221s2 + 2 e- ¡ Cd1s2 + 2 OH-1aq2 E°red = -0.76 V NiO1OH21s2 + H2O1l2 + e- ¡ Ni1OH221s2 + OH-1aq2 E°red = +0.49 V

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교과서 질문

A voltaic cell is constructed that uses the following half-cell reactions:

Cu⁺(aq) + e^- → Cu(s)

I₂(s) + 2 e^- → 2 I^-(aq)

The cell is operated at 298 K with [Cu⁺] = 0.25 M and [I^-] = 0.035 M.

(b) Which electrode is the anode of the cell?

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