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An automated external defibrillator (AED) is a medical device used to send an electric shock to the heart after cardiac arrest. A key component of the AED is the power source, or battery. Batteries used in AEDs need to have a good charge-to-weight ratio; they must be safe and reliable as well as rechargeable.Two types of rechargeable batteries used in early models of AEDs are the lead storage (also called lead-acid) battery and the nickel-cadmium (NiCd) battery. These batteries consist of multiple electrochemical cells that are connected in series to deliver a potential between 9 V and 18 V. A capacitor allows the AED to accumulate charge so that it can deliver between 300 V and 1,000 V.Some AEDs use a sealed lead storage battery. Lead storage batteries are robust and hold a charge for a long time. However, they have a low energy-to-weight ratio. Each lead storage cell delivers approximately 2.0 V, and a battery of four cells weighing 1000 g can provide 30 W∙h of energy.
Figure 1 Electron flow in a lead storage battery when discharging and chargingThe half reactions for the anode and cathode of a lead storage battery in 4 M of sulfuric acid (H₂SO₄) are shown in Reactions 1 and 2:
Reaction 1
Reaction 2
NiCd batteries have a higher energy-to-weight ratio than lead storage batteries but cannot hold as much charge. Each NiCd cell delivers approximately 1.3 V, and a single-cell battery weighing 120 g can provide 7.2 W∙h of energy.The half reactions at the anode and cathode for a NiCd battery in KOH are shown in Reactions 3 and 4:
Reaction 3

Reaction 4
-Which statement correctly describes the Pb electrode when the lead storage battery is charging as shown in Figure 1?

Question

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An automated external defibrillator (AED) is a medical device used to send an electric shock to the heart after cardiac arrest. A key component of the AED is the power source, or battery. Batteries used in AEDs need to have a good charge-to-weight ratio; they must be safe and reliable as well as rechargeable.Two types of rechargeable batteries used in early models of AEDs are the lead storage (also called lead-acid) battery and the nickel-cadmium (NiCd) battery. These batteries consist of multiple electrochemical cells that are connected in series to deliver a potential between 9 V and 18 V. A capacitor allows the AED to accumulate charge so that it can deliver between 300 V and 1,000 V.Some AEDs use a sealed lead storage battery. Lead storage batteries are robust and hold a charge for a long time. However, they have a low energy-to-weight ratio. Each lead storage cell delivers approximately 2.0 V, and a battery of four cells weighing 1000 g can provide 30 W∙h of energy.

Figure 1 Electron flow in a lead storage battery when discharging and chargingThe half reactions for the anode and cathode of a lead storage battery in 4 M of sulfuric acid (H₂SO₄) are shown in Reactions 1 and 2:

Reaction 1

Reaction 2
NiCd batteries have a higher energy-to-weight ratio than lead storage batteries but cannot hold as much charge. Each NiCd cell delivers approximately 1.3 V, and a single-cell battery weighing 120 g can provide 7.2 W∙h of energy.The half reactions at the anode and cathode for a NiCd battery in KOH are shown in Reactions 3 and 4:

Reaction 3

Reaction 4
-Which statement correctly describes the Pb electrode when the lead storage battery is charging as shown in Figure 1?

Quizplus · Accepted Answer

11ecba2d_11b6_57d3_a3bf_93e1601e9068_MD0008_00 When a battery is charging, it is an electrolytic cell, and when it is discharging, it is a galvanic cell. The difference between charging and discharging is determined by which electrode is the cathode and which is the anode. Although electron flow is in the opposite direction when a battery is charging as when it is discharging, electrons always flow from the anode to the cathode. Reduction occurs at the cathode, and oxidation occurs at the anode. PbSO₄ is the solid product that accumulates on both electrodes after the battery has been discharged. When the lead-acid battery is charging, electrons flow toward the lead electrode, making it the cathode. Because reduction occurs at the cathode, PbSO₄ is reduced. (Choice A) The lead electrode is the anode and is oxidized when the battery is discharging and the battery is acting as a galvanic cell, but it is the cathode when the battery is charging. (Choices B and D) In a lead storage (lead-acid) battery, H₂SO₄ is the electrolyte. Although the electrolyte serves as a charge carrier, it is neither oxidized nor reduced by the reaction. Educational objective: When a battery is discharging, it behaves as a galvanic cell, and when it is charging, it behaves as an electrolytic cell. In either case, oxidation occurs at the anode and reduction occurs at the cathode.

Passage An Automated External Defibrillator (AED) Is a Medical Device Used