Respuesta :
Q: Why is a homogeneous mixture not considered a pure substance?
Answer:
A pure substance can be separated by chemical means, while a mixture can be separated by physical means.
Explanation:
Mixtures are formed when two unreactive substances are mixed together. If the mixture is homogenous then it can be separated by distillation or by boiling the solvent leaving the solute behind. While, pure substances are either compounds or molecules which are connected through chemical bonds and require high energies to separate them hence, they can be separated by performing a chemical reaction which results in the formation of entirely new product.
__________________________________________________Q: How can a mixture of pigments be separated?
Answer:
By Chromatography
Explanation:
In chromatography a mixture of compounds are separated from each other on the basis of the difference in their polarity. Highly polar compounds travel less on the stationary phase while, the less polar compounds travel with mobile phase resulting in the separation with different Rf values.
__________________________________________________Q: Which of these is a unique property of acids?
Answer:
Taste Sour
Explanation:
Acids are those substances which either produce H⁺ ions in water, donate H⁺ to base or accepts lone pair of electrons. Among other physical properties the taste of acids is sour in nature while that of bases is bitter.
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Q: If a solution feels slippery and has a pH of 12, what is the solution?
Answer:
Basic
Explanation:
pH scale is used to determine the acidity and basicity of the substances. If the pH reads 7 it means that the substance is neutral in nature, if the pH is less than 7 than the substance is acidic in nature and if pH is greater than 7 then the substance is the base. Also, we know that bases are slippery in nature as they absorbs water from atmosphere rapidly resulting in slippery surface.
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Q: Which of these is an acid?
Answer:
Vinegar
Explanation:
As acids produces H⁺ ions in water or donate H⁺ to bases so Vinegar is an acid because vinegar is the solution of acetic acid which contains 5 % Acetic acid (CH₃COOH) and 95 % water which produces H⁺ as follow,
CH₃COOH ↔ CH₃COO⁻ + H⁺
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Q: What does pH measure?
Answer:
Concentration of Hydrogen ions in solution
Explanation:
pH expresses the acidity and alkalinity of a solution on logarithm scale. Mathematically it is given as,
pH = -log [H⁺]
and,
[H⁺] = 10^-pH
Therefore, pH determines the concentration of H⁺ ions in any given solution.
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Q: Solutions with high pH values have which of these properties?
Answer:
Feels Slippery
Explanation:
Option A is incorrect because it shows the taste of acids.
Option B is also incorrect because it is the property of acids as acids change the blue litmus paper to red.
Option C is correct as bases absorbs moisture from air and becomes slippery.
Option D is incoorect as acids can produce H₂ gas when treated with metals.
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Q: Acids turn litmus paper what color?
Answer:
From Blue to Red
Explanation:
The siplest test which is adopted to confirm the acidity or basicity of the substance is to carry out litmus paper test. Take a strip of blue litmus paper and dip it into unknown solution. If the color changes from blue to red then it is confirmed that the solution is acidic in nature. For bases, take red litmus paper. The base will change the color from red to blue.
