I am in lab working with a substance. When placed in pure water it completely dissociates and the pH of the water becomes 9.4. What do you think the substance is, and what happened to the hydrogen ion concentration of the water?
it is a base and the hydrogen ion concentration increased
it is an acid and the hydrogen ion concentration decreased
it is a base and the hydrogen ion concentration decreased
it is a buffer and the hydrogen ion concentration increased
The Correct Answer is C
A. it is a base and the hydrogen ion concentration increased: A base decreases H⁺ concentration by accepting H⁺ or releasing OH⁻.
B. it is an acid and the hydrogen ion concentration decreased: Acids increase H⁺ concentration, and a pH of 9.4 is basic, not acidic.
C. it is a base and the hydrogen ion concentration decreased: A pH of 9.4 is above 7, indicating a basic solution, and bases lower H⁺ concentration.
D. it is a buffer and the hydrogen ion concentration increased: A buffer resists changes in pH; it doesn't make pH jump to 9.4. Also, H⁺ would not increase in a basic environment.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. compounds that are ionically bonded together: Ionic compounds (like NaCl) dissociate easily in water because water's polarity can separate the positive and negative ions.
B. carbon-hydrogen chains, like saturated fats: These are nonpolar covalent compounds and are hydrophobic, so they don’t dissolve or dissociate well in water.
C. compounds that are covalently bonded together: Covalent bonds are strong and molecules remain intact in water; they don’t dissociate into ions.
D. compounds with covalent and some polar covalent bonds: These might partially dissolve but don’t dissociate readily into ions like ionic compounds do.
Correct Answer is B
Explanation
A. lipids: Lipids are not made of peptide bonds; they consist of fatty acids and glycerol.
B. enzymes: Enzymes are proteins, made of amino acids linked by peptide bonds. Denaturation alters the protein's structure and function.
C. nucleic acids: Nucleic acids (DNA/RNA) are composed of nucleotides, not peptide bonds.
D. eicosanoids: Eicosanoids are lipid-derived signaling molecules, not proteins.
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