# Category: Chemistry

### It is recommended that drinking water contain 16 ppm fluoride F for prevention of tooth decay Consider a reservoir

It is recommended that drinking water contain 1.6 ppm fluoride (F-) for prevention of tooth decay. Consider a reservoir with a diameter of 4.50x102m and a depth of 10.0m. How many grams of F- should be added to give 1.6 ppm? Fluoride is provided by hydrogen hexafluosilicate, H2SiF6. How many grams of H2SiF6 contain this […]

### A plain English explanation of how to calculate subatomic particle counts in anions and cations

A plain English explanation of how to calculate subatomic particle counts in positively or negatively charged atoms (a thorough explanation of the little plus and minus signs).

### Isotopes How to Calculate Isoptope Numbers and Determine Their Corresponding Number of Ionic Particles

Isotopes: How to Calculate Isoptope Numbers and Determine Their Corresponding Number of Ionic Particles

### How to identify an element and its isotopes by number of subatomic particles a thorough explanation in plain language

How to identify an element and its isotopes by number of subatomic particles (a thorough explanation in plain language).

### Determining the empirical formula of the oxide of magnesium

Determine the empirical formula of the oxide of magnesium. (Think carefully about the precision of each mass that you measured before you do this calculation. How many significant figures are justified for each mass?)

### 225 g of copper at 794 C C0385 JgC is dropped into 750mL of H2O at 225 C

22.5 g of copper at 79.4 C (C=0.385 J/(g.C)) is dropped into 75.0mL of H2O at 22.5 C What is the final temp in C

### 250g of H2O at 100 C is heated until the temp of the water is 10 C

25.0g of H2O at -10.0 C is heated until the temp of the water is 10 C. Given the following info how much heat was absorbed Cs = 2.06 J/(g.K), Cl = 4.184 J/(g.K), Cg = 2.01 J/(g.K) heat of fusion = 333 J/g heat of vaporazation = 2256 J/g Melting point of water = […]

### IGCSE

Simplified IGCSE Chemistry notes for students O level. It will help for the students to simply go through revision.

### Draw the general shape of the temperature energy graph for the cooling of acetone

Draw the general shape of the temperature energy graph for the cooling of acetone from 100 degrees celsius to -100 degrees celsius. (melting point = -95.4 degrees celsius, boiling point = 56.2 degrees celsius).

### A sample which is 20 Vendium 50 Rulium and 30 Gendium weighs 88 gramscc

A sample which is 20% Vendium, 50% Rulium and 30% Gendium weighs 8.8 grams/cc. A sample which is 60% Vendium, 20% Rulium and 20% Gendium weighs 9.8 grams/cc. A sample which is 30% Vendium, 30% Rulium and 40% Gendium weighs 8.8 grams/cc. What is the weight of pure Vendium, in gms/cc