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melisa1 [442]
2 years ago
14

How many grams of chromium metal are plated out when a constant current of 8.00 a is passed through an aqueous solution containi

ng cr3+ ions for 160. minutes?
Chemistry
1 answer:
Oliga [24]2 years ago
5 0
We can solve this without a concrete formula through dimensional analysis. This works by manipulating the units such that you end up with the unit of the final answer. Manipulate them by cancelling units that appear both in the numerator and denominator side. As a result, we must be left with the units of g. The current in A or amperes is equivalent to amount of Coulombs per second. Since this involves Coulombs, we will use the Faraday's constant which is 96,500 C/mol electron. The reaction is:

Cr³⁺(aq) + 3e⁻ --> Cr(s)

This means that for every 3 moles of electron transferred, 1 mole of Chromium metal is plated. The molar mass of Cr: 52 g/mol. The solution is as follows:

Mass of Chromium metal = (8 C/s)(60 s/1 min)(160 min)(1 mol e⁻/96,500 C)(1 mol Cr/3 mol e)(52 g/mol)
<em>Mass of Chromium metal = 13.79 g</em>
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How many molecules of CBr4 are in 250 grams of CBr4
Kazeer [188]

Answer:- 4.54*10^2^3 molecules.

Solution:- The grams of tetrabromomethane are given and it asks to calculate the number of molecules.

It is a two step unit conversion problem. In the first step, grams are converted to moles on dividing the grams by molar mass.

In second step, the moles are converted to molecules on multiplying by Avogadro number.

Molar mass of CBr_4  = 12+4(79.9)  = 331.6 g per mol

let's make the set up using dimensional analysis:

250g(\frac{1mol}{331.6g})(\frac{6.022*10^2^3molecules}{1mol})

= 4.54*10^2^3 molecules

So, there will be 4.54*10^2^3 molecules in 250 grams of CBr_4 .


8 0
2 years ago
Which process directly moves nutrients from plants to animals?
elena55 [62]

Answer:

Dude its A.Feeding

Explanation:

Its common scene that when u eat you are getting nutrient directly from the food. Come on Sponge Bob Me Boy

8 0
1 year ago
How much energy is required to heat 0.24 KG lutetium from 296.2K to 373.5 K? The specific heat for lutetium is 0.154 J/g-K
Olenka [21]

I’m not sure I need help with this question

6 0
2 years ago
A protein subunit from an enzyme is part of a research study and needs to be characterized. A total of 0.145 g of this subunit w
Hitman42 [59]

Answer:

The molar mass of the protein is 12982.8 g/mol.

Explanation:

The osmptic pressure is given by:

π=MRT

Where,

M: is molarity of the solution

R: the ideal gas constant (0.0821 L·atm/mol·K)

T: the temperature in kelvins

Hence, we look for molarity:

0.138 atm=M(0.0821\frac{l*atm}{mol*K} )(28+273K)

M=\frac{0.138atm}{(0.0821\frac{l*atm}{mol*K} )(301K)}= =5.584×10⁻³mol/l

As we have 2 ml of solution, we can get the moles quantity:

Moles of protein: 5.584×10⁻³\frac{mol}{l}\frac{1l}{1000ml}×2ml=1.117×10⁻⁵mol

Finally, the moles quantity is the division between the mass of the protein and the molar mass of the protein, so:

Moles=Mass/Molar mass

Molar mass= Mass/Moles=\frac{0.145g}{1.117*10^{-5}mol}=12982.8 g/mol

8 0
2 years ago
A liquid mixture containing 0.50 mole fraction benzene - toluene is contained in a storage vessel at 25°C and 1 atm. The vessel
Snowcat [4.5K]

Answer:

a. Yes, it is flammable.

b. It can cause hazard and carcinogenic effect.

Explanation:

A. Yes, the vapor in the vessel is flammable because it is an organic solvent with a very low boiling point. For this reason, less energy can vaporize it. Therfore, a little high temperature or energy causes it to be very reactive and flammable.

B. - Being flammable makes it hazardous, that is, it is capable of being ignited and can burn easily, which makes it really dangerous.

- It results in carcinogenic effect on the body. Substances that cause carcinogenic effect are capable of increasing the risk of cancer. They might contain compounds that can initiate tumor.

When the temperature is high, the risk of explosion increases. Due to the fact that at higher temperature, the kinetic energy of the atoms which result in an increase in the volume and finally blasting of the vessel.

7 0
2 years ago
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