The periodic table
Is Na more reactive than Mg?
Yes. The decreasing reaction list goes like this:
K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au
Are metal oxides acidic?
No. They're alkaline. Non-metal oxides are acidic.
You're holding onto someone at the edge of a building. The ground is 200m below. The person is about 40kg. What is their gravitational potential?
GPE=mass*gravity*height
80000 N=40*10*200
Explain what a vector is and give an example of a vector quantity we've learned.
Physical quantities that have size and direction. Velocity is a vector quantity.
Write down as many types of energy as you can in 30 seconds.
Kinetic, gravitational potential, elastic, chemical, internal, electrical, sound, nuclear.
Non-metal and metal bond: a
Non-metal and non-metal bond: b
Metal and metal bond: c
A: Ionic bond
B: Covalent bond
C: Metallic bond
Acid + Base = a
Acid + Metal = b
Acid + Metal Carbonate = c
a: Salt + Water
b: Salt + Hydrogen
c: Salt + Water + Carbon dioxide (CO2)
You have 2 pairs of boots. A lighter pair with a mass of 540g and a 100cm^2 wide base. And a heavier one is 720g and has a 120cm^2 wide base. You're going to visit the Sahara desert, which pair will be better to wear?
Pa=m/sa
5.4=540/100
6=720/120
The first pair exerts less pressure. You don't want to sink into the sand so it's better to wear that pair.
The force that resists 2 solids sliding/moving/rolling over each other.
Name a type of chemical reaction and give an example of it in the form of a chemical equation. (1 min)
Synthesis. Eg: Na+Cl=NaCl; H+O2=H2O
Decomposition. Eg: Electrolysis - H2O->H+O2
Neutralisation. Eg: HCl+NaOH=H2O+NaCL
Combustion. Eg: CH4 + 2O2 = CO2 + 2H2O
Displacement. Eg: Cl2+KI=KCl + I2
How is a covalent bond formed?
Two non-metals share electrons to stabilize each other. (Because the electronegativity difference is too small for the electrons to be fully transferred).
What is an amphoteric oxide?
Oxides that neutralize both acid and bases to produce salt and water.
You have a rock. You want to measure the density of the rock. How do you go about doing that?
First, put a fixed amount, like 100 cm^3 into a measuring cylinder. Record the volumes before and after the rock is placed inside. Calculate the difference in volume. Weigh the rock to find its mass.
Mass/Volume=Density (g/cm^3)
Why aren't you floating and why aren't you falling through the floor?
Gravity drags you closer to the core of the Earth. The ground below you pushes back against the force of your weight.
What is the electron configuration of Magnesium which has the atomic number of 12?
2,8,2.
Describe what is happening when an ionic bond is formed and what is the result.
An ionic bond is formed by the transfer of some electrons from one atom to another.
The atom losing electrons becomes positively charged. The atom gaining electrons becomes negatively charged. The electrostatic attraction between negative and positive ions creates an ionic bond.
What is pH measuring the presence of? Name one type of pH indicator and its reaction with acid and base.
pH measures the presence of H+
(More H+, more acidic. More OH-, more basic)
Litmus, universal, red cabbage.
Acid: red, hot, red
Base: blue, cold, greenish-yellow
You're pulling a suitcase at an angle of 60 degrees from the ground, with 80 N of force. You need to get to the check-in desk 20 m away. How much energy is needed to get to the desk?
Force(40)=Force(80)*cos(angle)[60]
Energy=Force*Distance
800 J=40*20
On a speed-time graph, what does a horizontal line mean?
The object is going at a steady speed.
Balance the equations (100 points each)(3 min):
Fe + Cl2 -> FeCl3
H2SiCl2 + H2O -> H8Si4O4 + HCL
C4H10O + O2 -> CO2 + H2O
FeBr3 + H2SO4 -> Fe2(SO4)3 + HBr
2Fe + 3Cl2 -> 2FeCl3
4H2SiCl2 + 4H2O -> H8Si4O4 + HCL
C4H10O + 6O2 -> 4CO2 + 5H2O
2FeBr3 + 3H2SO4 -> Fe2(SO4)3 + 6HBr
Why does the reactivity of group 1 elements increase down the table, but group 7 elements decrease down the table?
Uhh, so this is complicated.
Group 1 metals have 1 electron in their valence shells. The bigger the distance between the nucleus and the electron, the weaker the attraction between them.
>Therefore, the easier it is to lose it, making elements with more shells more reactive.
Group 7 metals have 7 electron in their valence shells. The more the shells there are, the less attraction there is.
>Therefore, it's less likely for another electron to be attracted, completing the valence shell. Making elements with more shells less reactive.
How do you test for Hydrogen, Oxygen, and CO2?
H: Makes flaming flint pop
O: Makes glowing flint light
CO2: Bubble gas through limewater and it will turn cloudy.
There's a person on a motorcycle.
The person is moving at 5 m/s. 30 seconds later, they've accelerated 0.5m/s^2. At that velocity, they're using 55000 J of kinetic energy. Find the mass of the person and motor cycle.
Change in velocity(15)=acceleration(0.5)*time(30)
Final velocity(20) = initial(5)+change(15)
Mass = Kinetic energy/(1/2v^2)
275kg=55000/(1/2(20^2))
A 10 meter long plank is marked on 9 separate places to indicate where it's 1m, 2m, 3m, and so on. Its 1m mark is placed on a pivot. Is the plank tipped to one side? Why? Why not?
Yes. The center of mass of the plank is at 5m and the contact force is at 1m. So, the plank will be tipped towards wherever the 5m mark is placed.
A 200g ball falls from a height of 5m and bounces back up to 4m. How much energy was used to bounce the ball back? And where did the left over energy go?
GPE(10)=0.2(kg)*10*5
0.2*10*4=8J
10-8=2J. This 2J probably became heat or energy used to deform the bouncy ball.