1.why is setting of curd a chemical changes ?
2. Define physical change.
3. define chemical change.
4. estate two characteristic of chemical change .
5. define galvanization .
6.what is rust .
7. what are the two important condition of rusting.
8.what happen when magnesium oxide is dissolved in water.
9. what happen when magnesium ribbon has burning in presence of air .
Answers
Answer:
Define of physical change.
Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds.
Answer:
1. Setting of curd is a chemical change because a new substance(lactic acid) is formed. The curd formed has a different taste than the original substance. Also, once the curd is formed, milk cannot be re-obtained from it. It is an irreversible change.
2. Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds.
3. Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.
4. Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.
5. The most common hot dipping process for industrial applications is galvanizing, which refers to the coating of zinc over iron or steels for rust proofing. It is an extremely versatile and easy means of providing corrosion protection for construction materials exposed to atmospheric conditions.
6. Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides and iron(III) oxide-hydroxide, and is typically associated with the corrosion of refined iron.
7. So, the presence of air and water vapor in air are two necessary conditions for the rusting of iron.
8. when magnesium oxide dissolved in water then it shows a reaction in which magnesium hydroxide Mg(OH) and hydrogen gas (H2) forms. These reactions found alkaline in nature. hope it will help you.
9. When the magnesium metal burns it reacts with oxygen found in the air to form Magnesium Oxide. ... After it burns, it forms a white powder of the magnesium oxide. Magnesium gives up two electrons to oxygen atoms to form this powdery product. This is an exothermic reaction.
Explanation:
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