Answer:
If a substance can be separated into its elements, it is a compound. If a substance is not chemically pure, it is either a heterogeneous mixture or a homogeneous mixture. If its composition is uniform throughout, it is a homogeneous mixture.
Explanation:
I hope it may help u
Answer:
- <em><u>A physical change has occurred, with no energy change.</u></em>
Explanation:
When a pencil lead is broken there is not change of any chemical properties, therefore it is not a chemical change, but just a physical change. In this case the change is just the number of pieces and dimensions.
Chemical changes always involve the formation of new different substances; the bonds between the atoms of the starting substances (reactants) breake and new bonds are formed leading to new substances (products) with different chemical composition (arrange of atoms). Chemical changes occur through chemical reactions.
Hence, if there is not change on the chemical composition, you think on physical changes. Physical changes include change in shape, size, state of matter (e.g. solid, liquid, gas). In the case of a pencil lead breaking, it is a change in shape and size.
Also, since energy has not been absorbed or released during the change, the energy of the pencil lead before having been broken is equal to the sum of the energies of the pieces of pencil lead obtained. So, this is a physical change with no energy changes.
Some examples of physical changes that include change in energy are the change of state (e.g. solid to liquid or liquid to gas) and the dissolution of a compound.
Answer:
mass of CO 2 = M r x number of moles of CO 2 = 44.0 × 0.010 = 0.44 g
Explanation:
Answer:
When there is heat at the bottom of this air or water, the air or water molecules in contact with the heat start to move, and the molecules spread apart. The heated air or water becomes less dense. It rises up until it gets to air or water with the same density as it has, and when it gets there, it pushes the air or water that was there out of the way. At the same time, new air or water fills the space that was vacated when the heated molecules rose up. The air or water that gets pushed out of the way falls down. This sets up a circular motion. Air or water is heated at the bottom, travels to the top, cools, gets denser, falls, is heated again and the whole cycle starts again. Convection does not occur in space because there is no gravity. Ovens work by convection. The heating coils at the bottom of the oven heat the air which climbs to the top, cools slightly, and falls down again.
Explanation:
Hello!
To solve this question, we need to use the
Avogadro's Number, which is a constant first discovered by
Amadeo Avogadro, an Italian scientist. He discovered that in a mole of a substance, there are
6,02*10²³ molecules. Using this relationship, we apply the following conversion factor:
So, 8,50 * 10²⁴ molecules of Na₂SO₃ represent
14,12 moles of Na₂SO₃
Have a nice day!
