Topic 1 Part 3 - Floating or sinking

Question 1

How many litres are in 1 m3

Answer 1

There are 1000 litres in 1 m3.

Question 2

If you filled the 1 m3 container right to the brim with water, what would be the mass of water?

Answer 2

1000 kg

Question 3

How much does 1 Litre weigh?

Answer 3

1 kg

Question 4

What is the density of a substance?

Answer 4

The mass of a substance divided by its volume.

Question 5

What is the SI Unit of Density?

Answer 5

The SI Unit of density is kg/m3 or Kilogram per cubic metre

Question 6

What is the density of water?

Answer 6

1000kg/1m3 = 1000 kg/m3

Question 7

What is the density of ice?

Answer 7

917kg/1m3 = 917 kg/m3

Question 8

Why does ice float on water?

Answer 8

Because the density of water 1000 kg/m3 is higher than the density of ice 917 kg/m3.

Question 9

Can you think of a molecular level explanation as to why ice is less dense than water?

Answer 9

The water molecules in ice are more ordered and spaced further apart than the molecules in liquid water. This means there is more empty space between the molecules in ice and so a smaller number of water molecules will fit into the same volume.

Question 10

Which elements is salt made of?

Answer 10

Salt is made of sodium and chlorine.

Question 11

Why can objects float better on water when salt is added?

Answer 11

Because sodium chloride has a higher density than water. Therefore, salt water has a higher density than just water.

Question 12

If the density of ice is 917 and the density of water is 1000, what percentage of an iceberg would be submerged?

Answer 12

91.7 %

Question 13

A sodium atom in sodium metal has 11 protons (and 12 neutrons) in its nucleus, which is surrounded by 11 electrons. If the sodium atom loses an electron, how many protons and electrons are left, and what is the overall electrical charge?

Answer 13

In losing one electron, the sodium atom reduces its number of electrons from 11 to 10, but the number of protons in the nucleus stays unchanged. The overall charge on what is left is therefore (+11 − 10) = +1 as there is one more proton than there are electrons.

Question 14

What is an ion?

Answer 14

The entity that remains after electrons are lost from ( or gained by) and atom.

Question 15

How is the sodium ion written?

Answer 15

Na+

Question 16

How would you write the ion derived from chlorine, in which the chlorine atom gains one electron?

Answer 16

By analogy with the sodium ion, the chloride ion is written as Cl−. Note the different term – a chlorine atom becomes a chloride ion in this case.

Question 17

What is ionic bonding?

Answer 17

The opposite electrical charges on two ions attract and this attraction is responsible for holding them together.

Question 18

What is a solute?

Answer 18

Is the substance that dissolves to make a solution.

Question 19

When salt dissolves into water, which is the solute?

Answer 19

Salt

Question 20

What is a solvent?

Answer 20

a liquid that has the ability to dissolve, suspend, or extract other materials, without chemical change to the material or solvent.

Question 21

When salt dissolves into water, which is the solvent?

Answer 21

Water

Question 22

What is the solution?

Answer 22

is a homogeneous (uniform) mixture in which a substance (known as the solute) dissolves in another substance (known as the solvent).

Question 23

Is water a polar or non-polar solvent?

Answer 23

Water is a polar solvent because water molecules have a slight separation of electrical charge within the molecule.

Question 24

Can you think of any compounds that don’t dissolve in water?

Answer 24

Oil doesn’t dissolve in water.

Question 25

Why does oil float in water?

Answer 25

Because oil is less dense than water

Question 26

why does sucrose dissolves in water?

Answer 26

The polar water molecules attract the negative and positive areas on the sucrose molecule making the sucrose molecules separate from each other and dissolve in water.

Question 27

What happens to the density of most pure liquids in regards to density and temperature?

Answer 27

In most pure liquids, density decreases with an increasing temperature.

Question 28

As temperature increases up to 4 degrees, what would you expect to happen to the density of water?

Answer 28

The density of the water increases.

Question 29

What happens to water when its density goes above 4 degrees?

Answer 29

Heating liquid water above 4 °C causes molecules to speed up and spread slightly apart, occupying a larger volume. This will result in a decrease of its density.

Question 30

What happens to the water molecules in a glass of water when you cool it down to 4 °C?

Answer 30

The water molecules will slow down and get closer together, occupying a smaller volume.

Question 31

At what temperature is the maximum density of water?

Answer 31

4 degrees

Question 32

What temperature will likely be at the bottom of a pond if the outside temperature is 15 to 0 degrees?

Answer 32

It reaches an ideal temperature of 4 degrees where water is the densest so it will sink.