Diagram Follow Up: What is it...element, compound or mixture?

An unknown, clear liquid is given to you in a beaker. You transfer the liquid from the beaker to a clean, empty test-tube, and begin to heat it. After a while, you see vapors (which on further analysis you discover are vapors of water) rising from the test-tube, and pretty soon, all that's left are a few crystals of salt stuck to the edges! Was that liquid an element, compound or a mixture?

Answer explanation

The constituents of a mixture can easily be separated by physical processes, which in this case, was the application of heat.

The salt had been dissolved in the water to form a true solution of common salt, where the particles of salt were invisible through the naked eye as well as through a microscope, resulting in the solution being absolutely clear.

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NGSS.MS-PS1-2

NGSS.MS-PS1-4

You have just won a block of pure 24-carat gold. Have you just procured an element, compound or mixture?

Answer explanation

Gold, like oxygen, hydrogen and over 100 other substances is classified as an element. Elements are further grouped into metals, non-metals and metalloids.

22-carat (or "karat") gold, or 22 parts of gold alloyed with 2 parts of silver or copper, is usually preferred to 24-carat (pure) gold in jewelery.

A dish is given to you, which contains a blackish-yellow powder. When you move a magnet over it, you are amazed to see black particles, (which you find out are iron) fly upwards and get stuck to the magnet, and all that's left in the dish is a yellow powder, which you discover to be sulphur (sulfur). What was originally in the dish?

Was your original powder an element, compound or mixture?

Answer explanation

The powder was a mixture of sulphur, which is yellow in colour, and iron, which is magnetic and blackish in colour.

When the magnet was passed over the mixture, the iron got attracted to it, leaving the sulphur in the dish. Hence in mixtures, the properties of the constituents aren't lost.

A substance is analysed in a laboratory, and when viewed under an electron microscope, it is revealed that it contains only one kind of atom. Is the substance an element, compound or mixture?

Answer explanation

An element is a substance which contains only one kind of atom.

Oxygen contains only atoms of oxygen, uranium contains only atoms of uranium, sodium contains only atoms of sodium. The structure of the atoms of an element defines its properties.

Water is what all life in the world depends on. Is it an element, compound or mixture?

Answer explanation

A molecule of water is made up of two atoms of hydrogen and one atom of oxygen, which means that it is made up of more than one kind of atom, and hence isn't an element.

Also, since it can only be broken down into hydrogen and oxygen (its constituent elements) by chemical processes (such as electrolysis), it is a compound.

Tags

NGSS.MS-PS1-1

Aqua regia was a liquid used by alchemists to separate silver from gold. Was aqua regia an element, compound or mixture?

Answer explanation

Aqua regia was a mixture of concentrated nitric acid (HNO3) and hydrochloric acid (HCl) and was used to dissolve gold, which would leave silver.

This gas is essential for us, and all other aerobic organisms, to survive. We inhale it along with the air we breathe (of which it forms approximately 21%) and it then helps in the oxidation of glucose in our bodies. When not in its molecular form, is it an element, compound or mixture?

Answer explanation

As you probably guessed, the gas is oxygen, of which the molecular formula is 'O2'.

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NGSS.MS-PS1-1

A magnesium ribbon is burnt in the air, to form the greyish oxide of magnesium - magnesium oxide (MgO). Is this oxide an element, compound or a mixture?

Answer explanation

Magnesium oxide is made up of atoms of two different kinds - magnesium and oxygen, and hence is not an element. The ratio of magnesium : oxygen in it is a constant 1:1, and hence it is a compound.

Tags

NGSS.MS-PS1-1

The air we breathe - is it an element, compound or mixture?

Answer explanation

Air is a mixture of several gases, with each of them retaining their own properties. Here's a brief outline of the composition of the air we breathe: Nitrogen - 78.1%; Oxygen - 20.9%; Argon - 0.9%; Carbon dioxide, methane, inert gases - 0.1%.

These are given 'symbols' like 'Ar', 'Zn', 'W' and 'Xe', and are arranged in a table called the Periodic Table. Are they elements, compounds or mixtures?

Answer explanation

While elements have 'symbols' to denote them, compounds have 'formulae' which show the presence of more than one element, such as 'H20' for water, 'NaCl' for common salt, etc.