Basis: 1 L of the substance.
(1.202 g/mL) x (1000 mL) = 1202 g
mass solute = (1202 g) x 0.2 = 240.2 g
mass solvent = 1202 g x 0.8 = 961.6 g
moles KI = (240.2 g) x (1 mole / 166 g) = 1.45 moles
moles water = (961.6 g) x (1 mole / 18 g) = 53.42 moles
1. Molality = moles solute / kg solvent
= 1.45 moles / 0.9616 kg = 1.5 m
2. Molarity = moles solute / L solution
= 1.45 moles / 1 L solution = 1.45 M
3. molar mass = mole solute / total moles
= 1.45 moles / (1.45 moles + 53.42 moles) = 0.0264
Answer:
Are basic:
[OH⁻] = 3.13x10⁻⁷M and [H₃O⁺] = 9.55x10⁻⁹M
Explanation:
A solution is basic when pH = - log [H₃O⁺] is higher than 7.
It is possible to convert [OH⁻] to [H₃O⁺] using:
[H₃O⁺] = 1x10⁻¹⁴ / [OH⁻]
a. [OH⁻] = 3.13x10⁻⁷M
[H₃O⁺] = 1x10⁻¹⁴ / [3.13x10⁻⁷M]
[H₃O⁺] = 3.19x10⁻⁸M
pH = - log [H₃O⁺] = 7.50
[OH⁻] = 3.13x10⁻⁷M is basic
b. pH = -log [H₃O⁺] = - log 0.000747M = 3.13.
This solution is not basic
c. [H₃O⁺] = 9.55x10⁻⁹M
pH = 8.02
This solution is also basic.
Some bad people will tend to forge dollar bills and make fake bills, giving them to cashiers and asking for it to be split into a different amount of bills so they are given real cash and wont be caught or they will buy things, return them and be given back real money and get away with it. This is obviously a crime because it's fake.
Since this process involves a matter-state change from solid to liquid, melting is occurring.
Ionic compounds have very strong intermolecular 'bonds': this is because it is formed by a metal atom donating one or more electrons to a non-metal atom in order to result in complete valence shells, with the effect that opposite ions are formed (opposites attract). Hence a large input of energy is needed to overcome these 'bonds' and form a liquid from the giant solid ionic lattice - therefore ionic compounds have high melting and boiling points.
Conversely a covalent bond occurs between two non-metal atoms - unlike ionic compounds which form giant ionic structures, covalent bonds are used to form molecules. These only have weak intermolecular forces, which need a small energy input to overcome: therefore the melting and boiling points will be much lower.
Considering that the compound has been taken from the freezer, which is 0 degrees celcius or lower, the state change has occurred at a low temperature. This makes it extremely likely that the compound is covalent.
In conclusion, the correct answer is d.
Answer:
b. Na+ leaves the salt bridge and enters enters the cathode
Explanation:
A galvanic cell or electrochemical cell depicts an oxidation -reduction half reactions (redox) reaction. it consists of two half cells ; one for the reduction reaction which involves the gain of electrons and the other for the oxidation reaction which involves the loss of electrons. One half cell contains the anode and oxidation occurs at the anode while the other half cell contains the cathode and reduction occurs at the cathode. The anode is usually connected to the cathode, a salt bridge is added to complete the circuit and allow current to flow. The salt bridge serves as a counter ions, they do not interfere with the electrochemical reaction but provides a passage for the migration of ions thereby preventing the cells from reaching equilibrium too quickly and thus the electrons in the salt are able to move along with any electrons.
In this galvanic cell, Cu at the anode losses two electrons to become Cu2+, and the electrons moves from the anode to the cathode where Mg2+ gain these two electrons to become negatively charged. Positively charged ions in the salt brigde Na+ will move to the cathode to pick negatively charged ions from the cathode solution. this helps to remove the strong negative charge from the cathode and allows the electrons to continue to move to the cathode.