Chemistry, 11.07.2019 12:00 sajawalkhan148

Select all the correct answers. properties of substances can be classified as physical or chemical properties. which statements describe chemical properties? a magnet is attracted to a piece of metal. a wire sags when weight is attached to it. silver tarnishes and becomes black when exposed to oxygen. water heated over a flame begins to bubble and evaporate. diesel fuel burns when it is heated.

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Answer from: chem1014

Silver tarnishes and becomes black when exposed to oxygen:

Diesel fuel burns when it is heated:

Explanation:

Chemical Changes are those changes in which the chemistry at molecular level is changed as the starting material is converted in to a new and different final material. This change takes place with the breaking of old bonds and forming of new bonds respectively.

Silver tarnishes and becomes black when exposed to oxygen:

This is a chemical change as Silver a white and lustrous starting material is being converted into a tarnish black final material. However, Silver doesn't readily react with oxygen at normal conditions. It readily react with Sulfur containing compounds in air and produces black compound as Ag₂S.

Diesel fuel burns when it is heated:

Diesel is a mixture of hydrocarbons ranging approximately from C₁₀H₂₀ to C₁₅H₂₈. When these hydrocarbons are burnt they produces a new materials i.e. CO₂ and H₂O.

C₁₀H₂₀ + 15 O₂ → 10 CO₂ + 10 H₂O

Hence, it is also a chemical reaction.

Answer from: emmajobaby

Silver tarnishes and becomes black when exposed to oxygen:

Diesel fuel burns when it is heated:

Answer from: Quest

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh $pcl_{3}$ +δh $cl_{2}$ ] - [δh $pcl_{5}$ ]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

Answer from: Quest

58750.08068 is the answer i think

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