Answer:
34.2 g
Explanation:
In the Hall-Heroult process, Al³⁺ (from Al₂O₃) is reduced to Al. The reduction half-reaction is:
Al³⁺ + 3 e⁻ ⇒ Al
We can establish the following relations:
- 1 A = 1 c/s
- 1 mole of e⁻ has a charge of 96468 c (Faraday's constant)
- 1 mol of Al is produced when 3 moles of e⁻ circulate
- The molar mass of Al is 26.98 g/mol.
Suppose a current of 6800 A is passed through a Hall-Heroult cell for 54.0 seconds. The mass of Al produced is:
Once for the water and once for the copper. Set up a table that accounts for each of the variables you know, and then identify the ones you need to obtain. Give me a moment or two and I will work this out for you.
Okay, so like I said before, you will need to use the equation twice. Now, keep in mind that when the copper is placed in the water (the hot into the cold), there is a transfer of heat. This heat transfer is measured in Joules (J). So, the energy that the water gains is the same energy that the copper loses. This means that for your two equations, they can be set equal to each other, but the copper equation will have a negative sign in front to account for the energy it's losing to the water.
When set equal to each other, the equations should resemble something like this:
(cmΔt)H20 = -(cmΔt)Cu
(Cu is copper).
Remember, Δt is the final temperature minus the initial temperature (T2-T1). We are trying to find T2. Since we are submerging the copper into the water, we can assume that the final temperature at equilibrium is the same for both the copper and the water. At a thermodynamic equilibrium, there is no heat transfer because both materials are at the same temperature.
T2Cu = T2H20
Now, the algebra for this part of the problem is a bit confusing, so make sure you keep track of your variables. If done right, the algebra should work out so you have this:
T2 = ((cmT1)Cu + (cmT1)H20) / ((cm)H20 + (cm)Cu)
Insert the values for the variables. Once you plug and chug, your final answer should be
26.8 degrees Celsius.
Explanation:
- The rule apply for the multiplication and division is :
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.
- The rule apply for the addition and subtraction is :
The least precise number present after the decimal point determines the number of significant figures in the answer.
a) 12.3 mm × 15.853 mm :
Three significant figures.
b) 72.98 · 15.830 ml
Three significant figures.
c) 12.3 mm + 15.853 mm
Three significant figures.
d) 172.3 cm - 15.853 cm
Four significant figures.
<span>As it travels through space, electromagnetic radiation hope this helps</span>
An element is a substance made from only one type of atom (e.g. oxygen is an element made up of only oxygen atoms).
An atom is the simplest form of an element that can exist, such as a lithium atom (Li).
Atoms of different elements can be combined together to create compounds, e.g sodium oxide (Na2O).
A molecule is a combination of 2 or more atoms that form chemical bonds. When these atoms are of the same element, they can be called molecules (e.g. O3 - ozone).
However when a molecule is made up of atoms of different elements, they are classified as compounds (e.g. CO2 - carbon dioxide).
So all compounds are molecules, but not all molecules are compounds.