Answer:
The period 4 alkaline-earth metal has the name Calcium. An isotope of this element having 20 neutrons has a mass number of 40.
Explanation:
Looking at the periodic table 4th row for the alkaline-earth metal, we can find Calcium which has an atomic number of 20 (or protons number, or z). The mass number is given by the sum of protons and neutrons. If the number of protons in this case is 20 and the number of neutrons is also 20, the mass number A = 40.
In the first situation: the mechanism of covection is the main form of heat transfer when warm air from a heater moves around and upward.
In the case of the metal pan the mechanism of heat transfer is conduction.
In the case of sunburn the mechanism is radiation.
In the case of an ice cube melting in a hand, conduction is the most important mechanism.
Answer:
204.5505 grams
2.5666 moles
Explanation:
For the first question, multiply 3.5 (# of moles) by 58.443 (g/mol for NaCl).
58.443 * 3.5
<em>I'll distribute 3.5 into 58.443.</em>
(3.5 * 50) + (3.5 * 8) + (3.5 * 0.4) + (3.5 * 0.04) + (3.5 * 0.003)
175 + 28 + 1.4 + 0.14 + 0.0105
203 + 1.4 + 0.14 + 0.0105
204.4 + 0.14 + 0.0105
204.54 + 0.0105
204.5505 grams
There are 204.5505 grams in 3.5 moles of NaCl.
For the second question, divide 150 (# of grams) by 58.443 (g/mol for NaCl). I'll convert both into fractions.
150/1 * 1000/58443
150000/58443
2.56660336 moles
2.5666 moles (rounded to 4 places to keep consistency with the first answer) are in 150 grams of NaCl.
The number of moles in 32.5g of aluminum chloride is approximately 0.250 moles.
