The correct answers are options C, that is, silver tarnishes and becomes black when exposed to oxygen, and option E, that is, diesel fuel burns when it is heated.
Chemical changes refer to the modifications in which the chemistry at molecular level is modified as the initial substance gets transformed into a new and different final substance. This change occurs with the dissociation of old bond and production of new bonds respectively.
Silver gets tarnished and becomes black when exposed to oxygen. This refers to a chemical change as silver a white and lustrous substance gets transformed into a tarnish black final substance. However, silver does not easily react with oxygen at usual circumstances. It easily reacts with sulfur comprising components in the air and generates black compound as Ag₂S.
Burning of diesel fuel when it is heated. Diesel refers to a mixture of hydrocarbons varying approximately from C₁₀H₂₀ to C₁₅H₂₈. When these hydrocarbons get burnt they generate novel substances, that is, carbon dioxide and water. Hence, it is also a chemical reaction.
Why chlorine has highest electron affinity than fluorine?
This is because the atomic radius increases down a group. The electron gained ends up in the outermost shell. ... Fluorine, which is higher up the group then chlorine, has a lower electron affinity. This is because the electrons in the outermost shell of a fluorine atom are closer together.
Explanation:
A chemical property is defined as the property that brings changes in chemical composition of a substance.
For example, flammability, combustion, reactivity, electronegativity etc are allchemical properties.
On the other hand, a property that does not bring any change in chemical composition of a substance is known as a physical property.
For example, shape, size, mass, density etc are all physical properties.
Thus, we can conclude that these may all be classified as chemical properties of a substance.
Answer:
Mario uses a hot plate to heat a beaker of 50mL of water. He used a thermometer to measure the
temperature of the water. The water in the beaker began to boil when it reached the temperature of
100'C. If Mario completes the same experiment with 25mL of water, what would happen to the boiling
point?
a) The water will not reach a boil.
b) The boiling point of water will increase.
c) The boiling point of water will decrease.
d) The boiling point of water will stay the same.
Explanation:
The reaction produces 2.93 g H₂.
M_r: 133.34 2.016
2Al + 6HCl → 2AlCl₃ + 3H₂
<em>Moles of AlCl₃</em> = 129 g AlCl₃ × (1 mol AlCl₃/133.34 g AlCl₃) = 0.9675 mol AlCl₃
<em>Moles of H₂</em> = 0.9675 mol AlCl₃ × (3 mol H₂/2 mol AlCl₃) = 1.451 mol H₂
<em>Mass of H₂</em> = 1.451 mol H₂ × (2.016 g H₂/1 mol H₂) = 2.93 g H₂
