Energetics I
What are the products of Zn + CuSO4 ?
ZnSO4 and Cu
What are the products of Cu + ZnSO4 ?
No product
We can explain the shape of the curve showing the rate of reaction by thinking about particles present and how they interact. This is called the ……………..?
Collision Theory
Adding a catalyst …………. reactions. The net effect of this is that there is ………….. in the position o equilibrium.
“speeds up“ AND “no change”
A wave produced by Tatsumaki travelling through a material has a frequency of 50 Hz and a wavelength of 0.40 m. How long does it take the wave to travel 100 m through this material?
5 seconds
Give a reason why the scientist does the experiment in a polystyrene cup.
Polystyrene is a good insulator of heat.
OR
Polystyrene is a poor conductor of heat.
OR
To reduce( minimise )heat loss.
The mass of anhydrous copper(II) sulfate used to make 25.0 cm3 of solution is 2.00 g. Calculate the amount, in moles, of anhydrous copper(II) sulfate in 2.00 g.
[Mr of anhydrous copper(II) sulfate = 159.5]
0.0125 moles
A rate of a reaction is given by R(t) = 4t + 5 moles/ dm3 s. Find a possible quadratic function of concentration, C(t). [C(0) = 1 mole/dm3].
C(t) = 2t2 + 5t + 1
……………………………..: the position of equilibrium shifts in the position with ΔH < 0.
Decreasing temperature
Tatsumaki raises a 200 kg set of weights from the floor to above his head in one movement. The bar is lifted through a vertical distance of 1.8 m. When the lift is completed the weightlifter holds the weights stationary for 2.0 seconds and then drops them to the floor.
At what speed do the weights hit the floor? (gravitational field strength = 10 N / kg)
6 m/s
In an experiment, when a student dissolves the anhydrous copper(II) sulfate in 50 cm3 of distilled water, the increase in temperature is 3.3 °C. [for water, c = 4.2 J / g / °C]
Calculate heat energy change in this experiment in kJ.
0.693 kJ
In an experiment, the student uses 1.70 g of the anhydrous copper(II) sulfate. Calculate the molar enthalpy change in kJ / mol. [Mr of CuSO4 = 159.5 and Q = 693 J]
64.766 kJ/mol
The concentration of a reactant, C , in a chemical reaction, is given by the function:
C(t) = (t-4)(2t+5)(t-4), where t is the time in seconds and the concentration C is in moles per dm³. Calculate the instantaneous rate of change of the concentration of reactant C at t=4 seconds.
120 moles / dm3 s
Changing the pressure affects the position of equilibrium in which at least …………………………………….., and………………….……………………………………………………………
“one of the reactants or products is a gas” AND
“the total number of gaseous molecules on both sides of the equation are differen.”
Tatsumaki has a circuit that consists of a 10 Ω resistor and a variable resistor connected in series with a 6.0 V battery. The variable resistor has a minimum resistance of 2.0 Ω and a maximum resistance of 20 Ω. What is the difference between the largest and smallest currents possible in this circuit?
0.3 A