Answer:
A. a system that can be affected by the outside environment, by an exchange of matter or energy
When the charged balloon is brought near the wall, it repels some of the negatively charged electrons in that part of the wall. Therefore, that part of the wall is left repelled.
<u>Explanation</u>:
- Balloons don't stick to walls. However, if you rub the balloon on an appropriate piece of material such as clothing or a wall, electrons are pulled from the other material to the balloon.
- The balloon now as more electrons than normal and therefore has an overall negative charge. Two balloons like this will repel each other.
- The other material now has an overall positive charge. Because opposite charges attract, the balloon will now appear to stick to the other material. If you didn't rub the balloon first, it's charge would be neutral and it wouldn't stick to the wall.
Answer:
0.0084
Explanation:
The mole fraction of BaCl₂ (X) is calculated as follows:
X = moles BaCl₂/total moles of solution
Given:
moles of BaCl₂ = 0.400 moles
mass of water = 850.0 g
We have to convert the mass of water to moles, by using the molecular weight of water (Mw):
Mw of water (H₂O) = (2 x 1 g/mol)+ 16 g/mol = 18 g/mol
moles of water = mass of water/Mw of water = 850.0 g/(18 g/mol) = 47.2 mol
The total moles of the solution is given by the addition of the moles of solute (BaCl₂) and the moles of solvent (water):
total moles of solution = moles of BaCl₂ + moles of water = 0.400 + 47.2 mol = 47.6 mol
Finally, we calculate the mole fraction:
X = 0.400 mol/47.6 mol = 0.0084
There are a couple of ways in which you can express the concentration of a solution, and here they are: gram per liter (g/L), molarity (M), parts per million (ppm.), and percents (%).
As you can see, only M appears in your answers, which means that the correct option should be (2) 3.5 M.
