Pure substances can or can not be chemically combined.
Pure substances can be either elements or compounds, but not mixture. Mixture are different substances mixing together without being chemically combined, such as air, which is a mixture of oxygen, carbon dioxide, water etc. Mixture can be separated by physical methods, like filtration or decantation.
Meanwhile, elements are the substances that cannot be further separated by any means. No matter physical or chemical methods. Examples of elements are oxygen, hydrogen, neon and all the other ones from the periodic table. Compounds are basically elements joining together, but they’re chemically combined which means their electrons (kind of subatomic particle) are either shared or given away. These elements can only be separated by chemical methods like electrolysis or heating.
Therefore, as long as the substance cannot be separated by physical methods, it can be considered as a pure substance. We can now conclude that pure substance can be (element) or can not be (compound) chemically combined.
The substances present before the reaction are the reactants. (As the reaction goes through, the substances that are produced are called the products of the reaction).
Answer:
1. Fe is reduced
2. Mn is Oxidized
3. N is oxidized
Explanation:
<em>Check the image below:</em>
Reducing agent is an element or compound that loses an electron to an electron recipient in a redox chemical reaction. oxidizing agent is a substance that has the ability to oxidize other substances — in other words to accept their electrons.
The force that accelerates objects towards Earth is gravity.
The liters in 3.25 g of ammonia 4.28 L
<u><em>calculation</em></u>
Step 1: find moles of ammonia
moles = mass÷ molar mass
From periodic table the molar mass of ammonia (NH₃) = 14 +(1×3 ) = 17 g/mol
3.25 g÷ 17 g/mol = 0.191 moles
Step 2: find the number of liters of ammonia
that is at STP 1 moles = 22.4 L
0.191 moles = ? L
<em>by cross multiplication</em>
={( 0.191 moles ×22.4 L) / 1 mole} = 4.28 L
