3.4.2 - Oxygen And Oxides

Question 1

Percentage of NITROGEN in the air :

Answer 1

. 78%

Question 2

Percentage of OXYGEN in the air:

Answer 2

. 21%

Question 3

Percentage of CARBON DIOXIDE in the air :

Answer 3

. 0.04%

Question 4

How do we measure the percentage of oxygen !?

Answer 4

. By reacting it with another element, often a metal.
- the air gradually DECREASES in volume until all of the oxygen has been added to the metal

Question 5

If the air didn’t decrease by 21% in an experiment, it could be because:

Answer 5

. The metal wasn’t HEATED for long enough (for all the oxygen to be reacted)

. There’s a LEAK in the apparatus

Question 6

Word equation for element combustion:

Answer 6

. Element + oxygen➡️ Element oxide

Question 7

When the element in Element Combustion is a METAL it’s is called…

Answer 7

. …A metal OXIDE and takes the form of a SOLID

Question 8

When the element in Element Combustion is a NON-METAL it’s is called…

Answer 8

. …A non-metal DIOXIDE and takes the form of a GAS

Question 9

Observations when combusting MAGNESIUM:

Answer 9

. Forms Magnesium Oxide
- BRIGHT WHITE LIGHT ⬜️💡
- WHITE POWDER IS FORMED ⬜️

Question 10

Observations when combusting SULPHUR:

Answer 10

. Forms Sulphur dioxide
- BLUE FLAME🟦

Question 11

Observations when combusting HYDROGEN:

Answer 11

. Forms water 💦
- squeaky pop 🐭🥤

Question 12

The CHEMICAL test for Oxygen:

Answer 12

. Glowing splint➡️ relights

• oxygen allows the wood in the splint to combust more efficiently

Question 13

Does [METAL OXIDE + WATER] form an acidic or an alkaline solution !?

Answer 13

. Alkaline solution (pH 8-14)🟦🟪

Question 14

Does [NON-METAL DIOXIDE + WATER] form an acidic or an alkaline solution !?

Answer 14

. Acidic solution (pH 0-6) 🟥