The amount of Li present to start the reaction is 55.18g
<u>Explanation:</u>
2Li + Br₂ → 2LiBr
Molecular weight of Br₂ = 159.808 g/mol
Mass of Br₂ present = 225 g
Moles of Br₂ present during the reaction = 225 / 159.808
m = 1.4
Molecular weight of LiBr = 86.845 g/mol
Mass of LiBr formed = 690 g
moles of LiBr produced = 690 / 86.845
m(LiBr) = 7.95
According to the balanced equation, 2 molecules of Li reacts to for 2 molecule of LiBr
So, 7.95 moles of LiBr would require 7.95 moles of Li
The molecular weight of Li is 6.941 g/mol
Thus, the amount of lithium present to start the reaction is

Therefore, the amount of Li present to start the reaction is 55.18g
Answer:
Force = mass × acceleration
Explanation:
The amount of force required to drag the object across the table is the product of the mass of the object and acceleration
Answer:
Y
Explanation:
The fulcrum is the point where the scissor blades are joined together. The force or effort is the end or handle of the scissors. The parts of a pair of pliers are similar to the scissors.
1) Forces acting on your body: force of gravity and normal reaction
2) Due to Newton's second law, N = mg
Explanation:
1)
When you sit on the computer, there are only two forces acting on you:
- The force of gravity, acting downward, of magnitude
, where m is your mass and
is the acceleration due to gravity, downward - The normal reaction exerted by the chair on you,
, acting upward
Your body is in equilibrium (it doesn't move), this means that the two forces balance each other, therefore:

2)
We can now apply Newton's second law of motion to this situation; this law states that the net force acting on a body is equal to the product between its mass and its acceleration. Mathematically,

where
is the net force
m is the mass
a is the acceleration
In this situation, the net force is

So the equation becomes

However, we observe that your body is at rest; therefore, the acceleration is zero:
a = 0
And therefore,

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