Answer:
.
Explanation:
-Synthesis reactions are reactions that appear when two distinct atoms or molecules engage to structure a specific molecule or compound. Most of the time, when a synthesis response occurs, electricity is launched and the response is exothermic. However, an endothermic consequence is additionally possible.
-A decomposition response starts offevolved from a single substance and produces extra than one substance; that is, it decomposes. One substance as a reactant and greater than one substance as the merchandise is the key attribute of a decomposition reaction. For example, in the decomposition of sodium hydrogen carbonate (also recognized as sodium bicarbonate)
-A single-replacement response (sometimes referred to as a single-displacement reaction) is a chemical response in which one aspect is substituted for every other factor in a compound, producing a new aspect and a new compound as merchandise
-A double-replacement response (sometimes referred to as a double-displacement reaction) takes place when components of two ionic compounds are exchanged, making two new compounds. A attribute of a double-replacement equation is that there are two compounds as reactants and two distinctive compounds as product
-A combustion response happens when a reactant combines with oxygen, many instances from the atmosphere, to produce oxides of all different factors as products; any nitrogen in the reactant is transformed to elemental nitrogen, N2. Many reactants, referred to as fuels, incorporate normally carbon and hydrogen atoms, reacting with oxygen to produce CO2 and H2O
Answer:
Copper turns green on exposure to air
Explanation:
Liquid water freezes to form ice: Physical change
Reason: Water can melt back when it becomes ice.
Copper turns green on exposure to air: Chemical change
Reason: The copper can not change back from the green state when it turns green.
Answer:
[OH⁻] = 4.3 x 10⁻¹¹M in OH⁻ ions.
Explanation:
Assuming the source of the carbonate ion is from a Group IA carbonate salt (e.g.; Na₂CO₃), then 0.115M Na₂CO₃(aq) => 2(0.115)M Na⁺(aq) + 0.115M CO₃²⁻(aq). The 0.115M CO₃²⁻ then reacts with water to give 0.115M carbonic acid; H₂CO₃(aq) in equilibrium with H⁺(aq) and HCO₃⁻(aq) as the 1st ionization step.
Analysis:
H₂CO₃(aq) ⇄ H⁺(aq) + HCO₃⁻(aq); Ka(1) = 4.3 x 10⁻⁷
C(i) 0.115M 0 0
ΔC -x +x +x
C(eq) 0.115M - x x x
≅ 0.115M
Ka(1) = [H⁺(aq)][HCO₃⁻(aq)]/[H₂CO₃(aq)] = [(x)(x)/(0.115)]M = [x²/0.115]M
= 4.3 x 10⁻⁷ => x = [H⁺(aq)]₁ = SqrRt(4.3 x 10⁻⁷ · 0.115)M = 2.32 x 10⁻⁴M in H⁺ ions.
In general, it is assumed that all of the hydronium ion comes from the 1st ionization step as adding 10⁻¹¹ to 10⁻⁷ would be an insignificant change in H⁺ ion concentration. Therefore, using 2.32 x 10⁻⁴M in H⁺ ion concentration, the hydroxide ion concentration is then calculated from
[H⁺][OH⁻] = Kw => [OH⁻] = (1 x 10⁻¹⁴/2.32 x 10⁻⁴)M = 4.3 x 10⁻¹¹M in OH⁻ ions.
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NOTE: The 2.32 x 10⁻⁴M value for [H⁺] is reasonable for carbonic acid solution with pH ≅ 3.5 - 4.0.
The fact that the student used different amount of water (another independent variable) is wrong with the experimental design
WHAT ARE THE COMPONENTS OF AN EXPERIMENT?
- An experiment aims at solving a scientific problem or answering a scientific question. An experiment should contain a variable being changed called INDEPENDENT VARIABLE and a variable being measured called DEPENDENT VARIABLE.
- In an ideal experiment, only one independent variable should be used while every other variable should be kept constant. This is done so as not to affect the result of the experiment.
In the experiment conducted by the student in this question, two independent variables were used i.e. the different amount of water and the different temperatures. This is what is wrong about the experimental design.
- In a nutshell, the fact that two independent variables were used by the student is what is wrong about the experimental design.
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