Answer: a) Balancing chemical equations
Explanation:
We are given that this student is struggling to have the "equations balanced to cancel out." This means that answer option A gives the specific problem they are facing, a) Balancing chemical equations. While they may be struggling to cancel things out, they say "I can't seem to have the equations balanced." This leads us to the specific answer.
The application of Hess's law involves balancing reactions and using stoichiometry to add or subtract equations, thus obtaining a desired reaction. The law states that the enthalpy change for a total process is the sum of enthalpy changes for individual steps. One can think of complex reactions as occurring in individual steps, helping to balance or cancel out equations.
In your question, you're grappling with the utilization of Hess's law and balancing or canceling out equations. To solve such problems with Hess's law, it's crucial first to understand what this law implies. Hess's law states that if a chemical process can be written as the sum of multiple steps, the enthalpy change of the total process equals the sum of the enthalpy changes for individual steps. This law works because enthalpy is a state function, which means that enthalpy changes depend mainly on the initial and final state, not the path through which the process passed.
For example, take the reaction of carbon with oxygen to form carbon dioxide. You can write this reaction as a direct process: C(s) + O₂(g) = CO₂(g). But you can also divide it into two steps: 1. Carbon and oxygen form carbon monoxide (C(s) + 02 (8) -> CO(g)), and 2. Carbon monoxide reacts with oxygen to form carbon dioxide (CO(g) + 1-0₂ (8) -> CO₂(g)). The reaction, when written as a sum of these steps, will give you the overall reaction, helping to balance or cancel out the equations.
The challenging aspect of Hess's law is the manipulation of equations to achieve cancellation and balance. Remember, stoichiometry rules allow us to change the quantities of reactants and products (but not their identity) when we have balanced equations. It's akin to mathematical equations, where one can multiply an entire equation by a constant to obtain an equivalent equation.
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Efficiency is the measure of how efficient a process is. It is used to assess the ability of a process in avoiding waste energy, materials, money and time in doing a desirable output. It is calculated as;
Efficiency = useful energy ouput / total energy input
Efficiency = 15(9.81)(20) / 3450 = 0.85
Output= m*g*h = 15*9.8*20 = 2,940J
Input= 3450J (given)
Efficiency = output/input = 2,940/3450 = 0.85% efficient
that time?
B)terrestrial planets and asteroids
C)dwarf planets like Pluto
Answer:
The apparent weight of a freely falling body is zero. When a body falls freely, it is falling with an acceleration =g. Thus the entire gravitational force acting on it is utilized in accelerating it and hence its weight is not felt.