Answer:
For these stars, the hotter they are, the brighter they are. The sun is a typical Main Sequence star. Dwarf stars are relatively small stars, up to 20 times larger than our sun and up to 20,000 times brighter.
Explanation:
Answer: C, B, A
Explanation:
C is the initial solution, because naoh has not been added yet
B is the midpoint of the titration. naoh has been added to the solution, but it has not fully reacted yet. You can tell that this one is the midpoint because there is still HF- in the diagram, which is not one of the products formed in the reaction.
A is the endpoint because the diagram shows that all products are fully formed. There is an increased amount of Na+ and H2O in the diagram and no HF- left.
PS. I tested this answer on the concentration of acetic acid post-lab (from mcgraw hill) earlier today and it said this was the right answer :) hope this helps
Answer: C₃H₂
Explanation:
1) Since you are told naphthelene is a hydrocarbon, you know that its chemical formula only has atoms of C and H.
2) Since combustion adds O but not C nor H, you know that all the C and H present in the products come from the naphthelene sample.
3) Calculate the amount of C in 13.20 grams of CO₂:
Use atomic masses:
C: 12.01 g/mol
O: 16.00 g/mol
⇒ molar mass of CO₂ = 12.01 g/mol + 2×16.01 g/mol = 44.01 g/mol
Proportion of C in 13.20 g of CO₂
12.01 g C / 44.01 g CO₂ = x / 13.20 g CO₂ ⇒
x = 13.20 g CO₂ × 12.01 g C / 44.01 g CO₂ = 3.602 g C
3) Calculate the mass of H in 1.80 g of H₂O
Atomic masses:
H: 1.01 g/mol
O: 16.0 g/mol
Molar mass H₂O = 18.02 g/mol
Proportion of H in 1.80 g H₂O
2.02 g H / 18.02 g H₂O = x / 1.80 g H₂O
x = 1.80 gH₂O × 2.02 g H / 18.02 gH₂O = 0.202 g H.
4) Calculate the number of moles of C and H in the masses calculated above
Number of moles of C = 3.602 g C / 12.01 g/mol = 0.3 mol
Number of moles of H = 0.202 g / 1.01 g/mol = 0.2 mol
5) Divide both amounts by the smallest one to calculate the proportion in moles:
C: 0.3 / 0.2 = 1.5 mol
H = 0.2 / 0.2 = 1 mol
Multiply by 2 to obtain integers:
C: 3
H: 2
6) Then the proportion leads to the empirical formula C₃H₂
Answer:
see explanation
Explanation:
The process of ionization to produce cations is endothermic. For formation of Ca⁺² two ionization steps need be illustrated as follows...
1st ionization step: Ca° + 590Kj => Ca⁺ + e⁻
2nd ionization step: Ca⁺ + 1151Kj => Ca⁺² + e⁻
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Net Ionization Rxn: Ca° + 1741Kj => Ca⁺² + 2e⁻
Answer:
The main component are electrons.
A chemical bond is any attractive interaction that keeps atoms short. This interaction can be directional as the bond between two atoms within a molecule, or non-directional as the electrostatic interaction that keeps the ions of an ion crystal in contact. It can be strong like the two previous examples, or weak as van der Waals interactions that are dipolar in nature.
Many models exist to describe these interactions. For example, the chemical bond between two atoms within a molecule can be described with the Lewis model or with a quantum model, like the theory of molecular orbitals. In both cases, the origin of the interaction is a sharing of electrons between the two partner atoms of the chemical bond.
There are three types of chemical bonds: single bonds, double bonds, and triple bonds. Indeed, the type of chemical bond depends on the number of electrons shared between the bound atoms:
* Simple bonds have 2 shared electrons.
* Double bonds have 4 shared electrons.
* Triple bonds have 6 shared electrons.
This number of electrons shared between the atoms depends on the electronic structure of these atoms and thus on the rules of the byte and the duet.
