Emma constructed a simple motor. When connected correctly, the coil of copper wire spins. Which of the following best describes
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Answer:
- Question 19: the three are molecular compounds.
- Question 20: CuSO₄.5H₂O
Explanation:
<em>Question 19.</em>
- C₂H₄
- HF
- H₂O₂
All of them are the combination of two kinds of different atoms in fixed proportions.
- C₂H₄: two carbon atoms per four hydrogen atoms
- HF: one hydrogen atom per one fluorine atom
- H₂O₂: two hydrogen atoms per two oxygent atoms
Thus, they all meet the definition of compund: a pure substance formed by two or more different elements with a definite composition.
Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.
Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.
<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.
Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol
Water is H₂O. Its molar mass is 18.015g/mol
Calling x the number of water molecules in the hydrate, the percentage of water is:
From which we can solve for x:
Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is:
- CuSO₄.5H₂O
Answer: (3) ppm
Explanation: Concentration is defined as the amount of solute dissolved in a known amount of the solvent or a solution.
Parts per million (ppm) is used to express the concentration when a very small quantity of solute is present in a large quantity of the solution. It is defined as the mass of solute present in one milion parts by mass of the solution.
L/s is used to express flow rate.
J/g is used to express energy per unit mass.
kPa is used to express pressure.