Answer:
The atomic number represents the number of protons
Explanation:
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To determine the fraction of carbon in morphine, we need to know the chemical formula of morphine. From my readings, the chemical formula would be <span>C17H19NO<span>3. We assume we have 1 g of this substance. Using the molar mass, we can calculate for the moles of morphine. Then, from the formula we relate the amount of carbon in every mole of morphine. Lastly, we multiply the molar mass of carbon to obtain the mass of carbon. We calculate as follows:
1 g </span></span> <span>C17H19NO<span>3 ( 1 mol / 285.34 g ) ( 17 mol C / 1 mol </span></span> <span>C17H19NO3</span>) ( 12.01 g C / 1 mol C) = 0.7155 g C
Fraction of carbon = 0.7155 g C / 1 g <span>C17H19NO<span>3 = 0.7155</span></span>
Answer:
If the pKa of the acid is low (negative), then the acid is strong.
Explanation:
Ka, <em>the acid ionization constant, </em>measures the strength of an acid in a solution. Stronger acids have higher Ka values.
We defined: pKa = -log[Ka]
This function is a decreasing function, meaning that pKa will be getting smaller and smaller, while increasing Ka (high values of Ka will have negative pKa values). Therefore, stronger acids (high values of Ka), will have low (negative) pKa values.
8. A. Density is independent of size (an intensive property).
9. B. The highest density is 1786 g/20cm^3, or 89.3 g/cm^3. The least is 512 g/20cm^3, or 25.6 g/cm^3. Therefore, the difference is 89.3 - 25.6, or 63.7 g/cm^3.
10. C. A bottle filled with air weighs less than one filled with marshmallows, because air is less dense than marshmallows.
11. D. The number represents the number of protons in the nucleus of the atom, as well as the atomic number of the element.
12. C. The number represents the atomic mass of the element, which is determined based on the relative abundance of each form of the element.
