Water being adsorbed by a paper towel is an example of a chemical change. true false

Hello!

There are two types of changes: physical and chemical.

A physical change is determined if it doesn't destroy matter, no change in size, shape, state, or color, or if nothing new is formed. You can most often see that it changes.

A chemical change is determined if it reacts with something else, matter will change after the reaction, a new substance is formed, or if there is a change in the physical and chemical properties.

So, if you were to soak a paper towel with water, you can see that nothing new is formed, and there is not a change in size, shape, state, or color. Therefore, this is a physical change.

Therefore, your answer is false.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%