You conduct an experiment where you use a single battery with a charge capacity of 900 mAh to precipitate an unknown metal from a salt solution that was leaking from an old battery. You use a vast excess of the salt, so the amount of metal condensed is limited by the battery. You obtain 3.368 g of the metal. You can assume that the metal was the only substance being reduced in the electrochemical cell and 100% of the listed battery charge is useable. If you were able to determine that the metal ion was a +2 ion, then which metal is it? This metal was used in batteries for a long time (even in “alkaline” batteries) due to its good electrochemical properties, but it is now being phased out. Why? (Show your work for full credit) PLS HELP
AM = atomic mass. valence is 2+
coulombs = amperes x seconds = 0.900 A x 60 min/hr x 60 s/min = 3,240 C.
96,485 C will deposit AM/2 grams of the metal
AM/2 x (3,240/96,485) = 3.368 g
Solve for AM. This looks like Hg to me and it's being phased out in batteries because of the environmental impact of Hg.
To determine the identity of the metal ion, we need to calculate the amount of charge involved in the reduction reaction using Faraday's law of electrolysis.
Step 1: Calculate the number of moles of charge transferred.
Given:
Charge capacity of the battery = 900 mAh
Conversion factor: 1 C = 1 A s = 1000 mA s
Converting charge capacity to Coulombs:
900 mAh = 0.9 Ah = 0.9 * 3600 C = 3240 C
Converting Coulombs to moles of charge:
1 mole of charge = 1 F = 96500 C
Number of moles of charge = 3240 C / 96500 C/mol = 0.0336 mol
Step 2: Calculate the number of moles of the metal ion.
Since the metal ion has a +2 charge, the number of moles of the metal ion will be half the number of moles of charge transferred.
Number of moles of metal ion = 0.0336 mol / 2 = 0.0168 mol
Step 3: Calculate the molar mass of the metal.
Molar mass of the metal = mass of metal / moles of metal
Given:
Mass of metal = 3.368 g
Moles of metal = 0.0168 mol
Molar mass of the metal = 3.368 g / 0.0168 mol ≈ 200 g/mol
Step 4: Determine the metal using the molar mass.
Based on the molar mass obtained, the metal with a molar mass of approximately 200 g/mol is most likely Zinc (Zn).
Step 5: Determine why Zinc is being phased out in batteries.
Zinc is being phased out in batteries because it is less environmentally friendly compared to other alternatives. During usage, zinc batteries generate waste and release harmful chemicals into the environment. Additionally, recycling zinc batteries can be challenging and energy-intensive. As a result, alternative battery technologies that are more sustainable and environmentally friendly, such as lithium-ion batteries, are being favored over zinc-based batteries.
To determine the metal ion being reduced in the electrochemical cell, we need to calculate the number of moles of metal that corresponds to the 3.368 g obtained.
First, let's convert the mass of metal obtained from grams to moles. To do this, we need the molar mass of the metal. Since we don't know which metal it is, we can calculate the molar mass for various possibilities.
Let's start with one possibility, assuming it's silver (Ag). The molar mass of silver is 107.87 g/mol.
Number of moles of silver = Mass of silver / Molar mass of silver
= 3.368 g / 107.87 g/mol
= 0.0312 mol
So, if the metal were silver, we would have obtained 0.0312 moles. Let's repeat the calculation for another possibility, assuming it's zinc (Zn). The molar mass of zinc is 65.38 g/mol.
Number of moles of zinc = Mass of zinc / Molar mass of zinc
= 3.368 g / 65.38 g/mol
= 0.0515 mol
So, if the metal were zinc, we would have obtained 0.0515 moles.
Comparing the number of moles for silver and zinc, we can see that the number of moles of zinc is significantly larger than the number of moles of silver. Therefore, the metal is most likely zinc (Zn) with 0.0515 moles.
Now, let's determine why zinc is being phased out in batteries despite its good electrochemical properties.
One of the main reasons why zinc is being phased out is its potential to corrode and cause leakage in batteries. Over time, zinc can react with the electrolyte and produce hydrogen gas, which can build up pressure and cause leakage or even rupture the battery. This can be dangerous and lead to environmental hazards.
To address these issues, newer battery technologies, such as lithium-ion batteries, have been developed. These batteries offer higher energy density, longer lifespan, and improved safety compared to traditional zinc-based batteries.
In addition, the recycling of zinc-based batteries can be challenging due to the need to properly handle and dispose of the potentially toxic materials. This has further led to a shift towards more environmentally friendly battery options.
Overall, the decision to phase out zinc in batteries is driven by the desire for improved safety, environmental considerations, and advancements in battery technology that offer greater performance and longevity.