the answer is D. John Newlands <3
Answer:
The traditional electrolyte for aluminium electrolysis is based on molten cryolite (Na3AlF6), acting as solvent for the raw material, alumina (Al2O3).Metals are found in ores combined with other elements. Electrolysis can be used to extract a more reactive metal from the ore.
Aluminum can and is used as both anodes and cathodes in electrochemical cells, but there are some peculiarities to using it as an anode in aqueous solutions. As you note, aluminum forms a passivating oxide layer quite readily, even by exposure to atmosphere. In an aqueous solution, if the potential is high enough, OH− and O2− are generated at the anode, which can then react with the aluminum to produce aluminum oxide. Al^3+ can also be generated directly. The electric field will draw the anions through the growing aluminum oxide layer towards the aluminum surface and the Al^3+ towards the solution, making the oxide layer grow both away from the electrode surface and into the surface of the electrode. In this way, coatings thicker than the normal passivation in air can be produced. However, aluminum oxide is a good electrical insulator, thus if a dense non-porous layer is grown, it will become impossible to pass current through it and growth will stop, leaving a relatively thin oxide layer (this is how the dielectric layers in electrolytic capacitors are made). This is the normal behaviour in aqueous solutions at near-neutral pH (5–7).
However, if a thick aluminum oxide layer is desired (e.g. to produce coatings on aluminum parts for dying or durability), maintaining porosity is necessary to avoid completely blocking access to the surface. One technique that is commonly used is using a low pH solution, which tends to redissolve some of the oxide and neutralize some of the formed OH−, leaving pores in the oxide layer through which the ions can travel and continue to react. These pores also give a good structure to retain dyes or lubricants, but generally need to be sealed after to protect against corrosion.
Answer:
0.718L of 0.81M HCl are required
Explanation:
Based on the reaction:
Cd(s)+2HCI(aq) → H2(g)+CdCl2(aq)
<em>1 mol of Cd reacts with 2 moles of HCl</em>
<em />
To solve this question we must, as first, find the moles of Cd. With the moles of Cd we can find the moles of HCl needed to react completely with the Cd. With the moles and the molarity we can find the volume:
<em>Moles Cd -Molar mass: 112.411g/mol-:</em>
32.71g * (1mol / 112.411g) = 0.2910 moles Cd
<em>Moles HCl:</em>
0.2910 moles Cd * (2 moles HCl / 1mol Cd) =
0.5820 moles HCl
<em>Volume:</em>
0.5820 moles HCl * (1L / 0.81moles) =
<h3>0.718L of 0.81M HCl are required</h3>
So in a chemical change, the product would loses its properties, would form new products and would not be easily reversed.
In a physical change, the products WILL NOT lose any of their properties, WILL NOT form any new products and WILL be easily reversed.
Talking about Water turning to ice I would say it’s all about physical change and not chemical change.
But I would suggest you to either make a research about it or ask your teacher :))
Answer:
A) Test(independent) variable is bat wings.
B) Result (dependent) Variable is the Polyjuice Potion.
C) Cauldrons and fire
Explanation:
A) A test/independent variable is the variable that is being tested in the experiment or research and it is not affected by other variables in the experiment.
Now, in this experiment, what is being tested is are the bat wings.. Thus;
Test(independent) variable is bat wings.
B) Result (dependent) Variable is a variable that depends on the independent variable being tested. From the question, the result is the Polyjuice Potion.
Thus, Result (dependent) Variable is the Polyjuice Potion.
C) The constants are things that don't change with respect to any of the other variables. In this case, they are; cauldrons and fire
