The mass of pentane the student should weigh out is
The density of pentane is 0.626 gcm-3
To calculate the mass of pentane following expression is used,
(Density is defined as the mass divide by volume)
Density = mass / volume
mass of pentane = Density of pentane * Volume of pentane
mass of pentane = 0.626 gcm-3 * 45.0 mL
= 28.17 g
Here the unit of mass of pentane is g,
However the unit of density is gcm-3 and unit of volume is mL i.e. cm3
Hence, Mass = gcm-3 * cm3
Mass = g
The mass of pentane the student should weigh out is 28.17g
Learn more about Density on
brainly.com/question/1354972
#SPJ1
Given that,
Work done by the system = 125 J
Energy released when it cools down = 438 J
To find,
The change in internal energy.
Solution,
As heat is released by the system, Q = -438 J
Work done by the system, W = -125 J
Using the first law of thermodynamics. The change in internal energy is given by :

So, the change in internal energy is 563 J.
Answer
Depends on type of mixture. But I think separating the different sized particles through filtration would be a sufficient answer for middle school level unless they have taught you about other mixtures.
Explanation:
Hey,
There are thousands of way to separate mixtures. Each way is specific to the type of mixture. If the mixture is homogeneous processes like distillation can be employed. For heterogeneous mixture filtration can be used to separate particles of different sizes.
To see the mole to mole ratio. If you have this then you see how many moles are used for other reactants/products in the equation