Flash point vs fire point: what is the difference?

Self-tutoring about safe temperature to heat cooking oil led the tutor to seek the difference between flash point and fire point.

At the flash point, the vapor is ignitable but will only burn with a continuous source of ignition. At the fire point, the vapor, once ignited, will burn independently, even if the ignition source is removed.

Source:

www.differencebetween.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Chemistry: acid nomenclature: hypo acids

Tutoring chemistry, naming acids might arise. The tutor brings up a time to use hypo in naming an acid.

From a simple point of view, the hypo acid has one less oxygen than the -ous acid. For example:

chlorous acid: HClO2

hypochlorous acid: HOCl

Source:

Mortimer, Charles E. Chemistry, sixth ed. Belmont: Wadsworth, 1986.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Biology: what mineral form of calcium is found in bones?

Tutoring biology, the question about calcium in bone – specifically, which mineral form it takes – might arise. The tutor discusses it.

The hardness of bone comes from the presence of hydroxyapatite:

hydroxyapatite:

Ca5(PO4)3OH

found in bones and giving them their hardness.

Source:

answersingenesis.org

www.iofbonehealth.org

www.fluidnova.com

www.w3schools.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Chemistry: what are degenerate orbitals?

Tutoring chemistry, you sometimes cover bonding. The tutor defines degenerate orbitals.

Degenerate: being two separate objects with a single, identical value.

The 1s orbitals of two separate hydrogen atoms are degenerate because, isolated from each other, they share a single, identical energy level.

When the two hydrogen atoms bond together, their separate 1s orbitals merge into two hybrids, one of high energy, the other low. There are still two orbitals, but each of unique energy level, so the degeneracy is erased.

Such is how I understand degenerate orbitals from the reading:)

Source:

Mortimer, Charles E. Chemistry, 6th ed. Belmont: Wadsworth, 1986.

chemistry.stackexchange.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Chemistry: disproportionation

Tutoring chemistry, you likely touch on redox. The tutor shows a disproportionation.

disproportionation: a reaction in which the same species both oxidizes and reduces.

Example:

Cu+ → Cu2+ + e E=-0.153
Cu+ + e → Cu(s) E=0.521

The above disproportionation, theoretically, is spontaneous, since the potentials (E) sum positive (0.368V in this case).

Source:

Mortimer, Charles E. Chemistry, 6th ed. Belmont: Wadsworth, 1986.

sites.chem.colostate.edu

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Chemistry: groups IB and IIB

Tutoring chemistry, the periodic table is important. The tutor mentions a peculiarity of it.

The transition metals are the elements in the middle of the periodic table, starting the fourth row from the top. Their first element is scandium (Sc).

On some periodic tables, you’ll notice that scandium (Sc, 21) is under group IIIB, then follows titanium (Ti, 22) under IVB, and so on. However, if you continue across, you’ll notice that copper (Cu, 29) is under IB, then zinc (Zn, 30) is under IIB. Why do IB and IIB appear at the right side, while IIIB appears at the left?

Beginning with scandium, the 3d subshell is being filled, but 4s, in the shell above, already is. Scandium is 3d14s2. At nickel (Ni, 28), the 3d subshell has 8 electrons, the 4s, 2. However, at copper (Cu, 29), the 3d subshell gains two electrons to reach 3d10, while 4s drops to 4s1. Zinc has 3d104s2. Perhaps it’s the refilling of the outer s subshell that defines IB and IIB at the right side of the transition metals.

In the next period, silver (Ag, 47) has 5s1, while cadmium (Cd, 48) has 5s2. However, the filling of 4d happened back at palladium (Pd, 46).

One more period down, gold (Au, 79) has 6s1, while mercury (Hg, 80) has 6s2.

Source:

Mortimer, Charles E. Chemistry, 6th ed. Belmont: Wadsworth, 1986.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Physics, chemistry: closed system vs isolated system

Tutoring physics or chemistry, definitions are always important. The tutor compares closed system with isolated system.

A closed system cannot lose or gain matter; it cannot exchange matter with the surrounding environment.

An isolated system is closed as above, but also with regards to energy. That is to say, an isolated system cannot exchange matter or energy with the surrounding environment.

Source:

Giancoli, Douglas C. Physics, 5th ed. New Jersey: Prentice Hall, 1998.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Biology, chemistry: the difference between cellulose and lignin

Tutoring biology, you deal with organic molecules. The tutor mentions the difference between lignin and cellulose.

Cellulose and lignin are both found in cell walls.

Cellulose is composed of many glucose units bonded together.

Lignin, on the other hand, consists of phenyl propane units bonded together.

Therefore, cellulose is a polysaccaride, or starch, whereas lignin is aromatic.

Source:

Mader, Sylvia S. Inquiry into Life, 9th ed. Toronto: McGraw-Hill, 2000.

www.icfar.ca

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Chemistry: why nitric acid is more acidic than nitrous

Tutoring chemistry, the concept of acid strength is important. The tutor explains why nitric acid is more acidic that nitrous.

Nitric acid (HNO3) and nitrous acid (HNO2) both have N as the central atom, and share the structure H-O-N….However, nitric acid has an extra oxygen on the other side of N, which causes more electron drain from the N atom. The N atom, in turn, pulls electron density from the O between it and the H. With less electron availability, the O adjacent to H in HNO3 can less effectively attract H+, so loses it more readily than does HNO2.

Source:

Mortimer, Charles E. Chemistry, sixth ed. Belmont: Wadsworth, 1986.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Calculator usage: linear regression on the Casio fx-991ES PLUS C

Tutoring statistics, you cover linear regression. The tutor shows how to get a best-fit line on the Casio fx-991ES PLUS C.

Let’s imagine you have the following data

x y
10.1 14.2
17.3 19.5
25.4 22.9
40.0 31.8

Furthermore, you’d like to find a line of the form y=A+Bx that fits the data. Here’s how you might do it using the Casio fx-991ES PLUS C:

  1. Press Mode then 3 for Stat mode.
  2. Press 2 for y=A+Bx
  3. In the table that appears, enter the x and y values.
  4. After all the x and y values have been entered, press AC.
  5. Now, press Shift then 1.
  6. Press 5
  7. You’ll see choices for A, B, and other stats. Select the one you want, then press Enter.
  8. If, for example, you select A first and get its value, press Shift then 1 then 5 to return to the other choices. You can then choose B.

Source:

Casio fx-991ES PLUS C User’s Guide.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.