First of all, there are five types of solid materials:
Metallic solids which are solids composed of metal atoms that are held together by metallic bonds.
Network solid is a chemical compound in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material.
Molecular solid is a solid consisting of discrete molecules.
Ionic solid is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding.
Amorphous solid is non-crystalline solid that lacks the long-range order that is characteristic of a crystal.
Now, after the defined all the types of solid materials in the equation lets to solve it.
A. the answer is the network solids, because covalent bonds are relatively strong, covalent are typically characterized by hardness, strength, and high melting points.
B. the answer is the metallic solids, due to that heat conduction occurs when a substance is heated and the particles will gain more energy vibrating more. These molecules then bump into nearby particles and transfer some of their energy to them and in metals this process have a higher probability than in the case of other solids due to the nature of the chemical bonds. It also has a range of hardness due to the strength of metallic bonds which varies dramatically.
C. the answer is the ionic solid; due to positive and negative ions which are bonded to form a crystalline solid held together by charge attractions.
Problem One (left)
This is just a straight mc deltaT question
<em><u>Givens</u></em>
m = 535 grams
c = 0.486 J/gm
tf = 50
ti = 1230
Formula
E = m * c * (ti - tf)
Solution
E = 535 * 0.486 * ( 1230 - 50)
E = 535 * 0.486 * (1180)
E = 301077
Answer: A
Problem Two
This one just requires that you multiply the two numbers together and cut it down to 3 sig digits.
E = H m
H = 2257 J/gram
m = 11.2 grams
E = 2257 * 11.2
E = 25278 to three digits is 25300 Joules. Anyway it is the last one.
Three
D and E are both incorrect for the same reason. The sun and stars don't contain an awful lot of Uranium (1 part of a trillion hydrogen atoms). It's too rare. The other answers can all be eliminated because U 235 is pretty stable in its natural state. It has a high activation complex.
Your best chance would be enriched Uranium (which is another way of saying refined uranium). That would be the right environment. Atomic weapons and nuclear power plants (most) used enriched Uranium. You can google "Little Boy" if you want to know more.
Answer: B
Four
The best way to think about this question is just to get the answer. Answer C.
A: incorrect. Anything sticking together implies a larger and larger result. Gases don't work that way. They move about randomly.
B: Wrong. Heat and Temperature especially depend on movement. Stopping is not permitted. If a substance's molecules stopped, the substance would experience an extremely uncomfortable temperature drop.
C: is correct because the molecules neither stop nor do they stick. The hit and move on.
D: Wrong. An ax splitting something? That is not what happens normally and not with ordinary gases. It takes more energy that mere collisions or normal temperatures would provide to get a gas to split apart.
E: Wrong. Same sort of comment as D. Splitting is not the way these things work. They bounce away as in C.
Five
Half life number 1 would leave 0.5 grams behind.
Half life number 2 would leave 1/2 of 1/2 or 1/4 of the number of grams left.
Answer: 0.25
Answer C
Answer:
to which cations from the salt bridge migrate
Explanation:
A voltaic cell is an electrochemical cell that uses spontaneous redox reactions to generate electricity. It's composed of a cathode, an anode, and a salt bridge.
In cathode, the substance is gaining electrons, so it's reducing, in the anode, the substance is losing electrons, so it's oxidating. The flow of electrons is from the anode to the cathode.
The salt bridge is a bond between the cathode and the anode. When the redox reaction takes place, the substances produce its ions, so the solution is no more neutral. The salt bridge allows the solutions to become neutral and the redox reaction continues.
So, the cathode produces anions, which goes to the anode, and the anode produces cations, which goes to the cathode. Then, the cathode n a voltaic cell is the electrode to which cations from salt bridge migrate and where the reduction takes place.
Initial moles of C₆H₅COOH = 500/1000 × 0.10 = 0.05mol
Initial moles of C₆H₅COONa = 500/1000 × 0.10 = 0.05 mol
initial pH = Pka + log([C₆H₅COONa/ moles of C₆H₅COOH)
4.19 = pKa + log(0.05/0.05)
→pKa = 4.19
C₆H₅COOH + NaOH → C₆H₅COONa ₊ H₂o
moles of NaOH added = 0.010 mol
moles of C₆H₅COOH = 0.05 - 0.025 = 0.025 mol
Final pH = pKa + log([C₆H₅COONa)/[ C₆H₅COOH])
=pKa + log(moles of C₆H₅COONa/moles of C₆H₅COOH)
= 4.19 + log(0.025/0.075)
4.29
