Year 9 Science Chemistry 2

A chemical change is difficult to reverse where as a physical change is easily reversible.

Endothermic involves the absorption of heat.

an example of a corrosion reaction.

A chemical change involves the creation of new substances with different chemical properties. This can occur through various processes such as a reaction between two or more substances, the breakdown of a compound into its components, or the rearrangement of atoms within a molecule. In contrast, a physical change does not result in the formation of new substances, but rather alters the state or appearance of a material. Therefore, the statement that a chemical change involves the formation of at least one new substance is true.

A corrosion reaction refers to the process where a metal is gradually deteriorated or "eaten away" by substances present in the air or water. This happens due to chemical reactions between the metal and the corrosive substances, which can lead to the formation of rust or other forms of corrosion on the metal surface. Carbon dioxide causing an object to implode, ham forming mold, and liquid evaporation due to a reaction with a transitional metal are unrelated to corrosion reactions.

The Law of Conservation of Mass is a fundamental principle in chemistry, stating that matter cannot be created or destroyed in a chemical reaction. This means that the total mass of reactants before the reaction equals the total mass of the products after the reaction. While the substances involved may change form, the amount of matter remains constant, ensuring that mass is conserved throughout the process. This law is crucial for understanding chemical equations.

When naming compounds a metal goes before a non-metal.

Ham's atoms are reacting to form a new substance, all the rest are reversible (hot dog is just warmed, state of butter and water is just changed)

A combustion reaction is when substances react with oxygen to release heat.

Zinc breaking down into zinc oxide and carbon dioxide is an example of a decomposition reaction. In this reaction, a single compound (zinc) is broken down into two or more simpler substances (zinc oxide and carbon dioxide). This is different from a corrosion reaction, which involves the gradual deterioration of a material due to chemical reactions with its environment, and from a combustion reaction, which involves the rapid reaction of a substance with oxygen, typically resulting in the release of heat and light.

In a chemical reaction new atoms are not formed or created but the existing atoms are rearranged into new substances.

In combustion reactions hyrdocarbons combine with oxygen in the air to form carbon dioxide gas and water vapour.

Galvanising is the process of coating metal with zinc to protect it from reacting with water and oxygen. This process forms a protective layer on the metal surface, preventing corrosion and extending its lifespan.

The Law of Constant Proportion states that a compound, no matter how it is formed, always contains the same relative amounts of each element. This means that the ratio of elements in a compound is always constant, regardless of the method used to create the compound. For example, if a compound is made up of elements A and B, it will always have the same ratio of A to B, regardless of whether it is formed through a chemical reaction or any other means. This law helps to explain the consistent composition of compounds and allows chemists to predict the amounts of elements present in a compound.

zinc rusting is corrosion, zinc carbonate decopmosing is decompostion and sodium hyrdoxide with acid is a neutralisation reaction.

The other two (rust and egg) involve change of atoms.

State change and reactants solidifying are not indications of chemical change because they are physical changes. In a state change, the substance transitions from one state of matter to another (e.g. from solid to liquid or gas), but its chemical composition remains the same. Reactants solidifying refers to a substance returning to a solid state, but this does not involve a chemical reaction. Chemical changes, on the other hand, involve the formation of new substances with different chemical properties.