Answer:
Bohr's model of the hydrogen atom is based on three postulates:
1) An electron moves around the nucleus in a circular orbit,
2) An electron's angular momentum in the orbit is quantised,
3) The change in an electron's energy as it makes a quantum jump from one orbit to another is always accompanied by the emission or absorption of a photon. Bohr's model is semi-classical because it combines the classical concept of electron orbit (postulate 1) with the new concept of quantisation ( postulates 2 and ).
Answer:
a
Explanation:
a mixture is a material made up of two or more different substances which are not chemically combined. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions, suspensions and colloids.
Answer:
The correct answer is "Iron and oxygen act as Fe3+ and O2− ions respectively, forming rust (Fe₂O₃) in the presence of water by the formation of an ionic bond".
Explanation:
Rust is formed when iron reacts with oxygen in the presence of water (either if the iron is submerged or exposed to moisture in the air), forming the chemical compound Fe₂O₃. The presence of water is needed for rust formation because iron and oxygen act as ions when they are exposed to water, particularly Fe3+ and O2− ions respectively. The bond formed between these two elements are ionic bonds, because it is comprised of the reaction between a metal (iron) and a non-metal (oxygen).
Answer:
429.4 kJ are absorbed in the endothermic reaction.
Explanation:
The balanced chemical equation tells us that 1168 kJ of heat are absorbed in the reaction when 4 mol of NH₃ (g) react with 5 mol O₂ (g).
So what we need is to calculates how many moles represent 25 g NH₃(g) and calculate the heat absorbed. (NH₃ is the limiting reagent)
Molar Mass NH₃ = 17.03 g/mol
mol NH₃ = 25.00 g/ 17.03 g/mol = 1.47 mol
1168 kJ /4 mol NH₃ x 1.47 mol NH₃ = 429.4 kJ
Answer:
2 AgNO₃(aq) + Ca(BrO₃)₂(aq) ⇒ Ca(NO₃)₂(aq) + 2 AgBrO₃(s)
2 Ag⁺(aq) + 2 NO₃⁻(aq) + Ca²⁺(aq) + 2 BrO₃⁻(aq) ⇒ Ca²⁺(aq) + 2 NO₃⁻(aq) + 2 AgBrO₃(s)
2 Ag⁺(aq) + 2 BrO₃⁻(aq) ⇒ 2 AgBrO₃(s)
Explanation:
The question is missing but I think it must be about the chemical equations.
Let's consider the molecular equation that occurs when a solution of silver nitrate and a solution of calcium bromate react.
2 AgNO₃(aq) + Ca(BrO₃)₂(aq) ⇒ Ca(NO₃)₂(aq) + 2 AgBrO₃(s)
The complete ionic equation includes all the ions and the insoluble species.
2 Ag⁺(aq) + 2 NO₃⁻(aq) + Ca²⁺(aq) + 2 BrO₃⁻(aq) ⇒ Ca²⁺(aq) + 2 NO₃⁻(aq) + 2 AgBrO₃(s)
The net ionic equation includes only the ions that participate in the reaction and the insoluble species.
2 Ag⁺(aq) + 2 BrO₃⁻(aq) ⇒ 2 AgBrO₃(s)
