Answer:
b. 6.02 x 1023 molecules
Explanation:
The formula mass of ammonia is 14 + 1 × 3 = 17.
The number of moles in 27.6g ammonia is 27.6 ÷ 17 = 1.62 mol.
A mole is 6.02 × 10²³, so the number of hydrogen atoms in a 1.62 moles of ammonia is 1.62 × 6.02 × 10²³ × 3 = 2.93 × 10² atoms.
Answer:
Enthalpy of vaporization = 30.8 kj/mol
Explanation:
Given data:
Mass of benzene = 95.0 g
Heat evolved = 37.5 KJ
Enthalpy of vaporization = ?
Solution:
Molar mass of benzene = 78 g/mol
Number of moles = mass/ molar mass
Number of moles = 95 g/ 78 g/mol
Number of moles = 1.218 mol
Enthalpy of vaporization = 37.5 KJ/1.218 mol
Enthalpy of vaporization = 30.8 kj/mol
sodium chloride is a compound that is stable because its constituent elements namely chlorine and sodium have formed ionic bonds with each other and their outer energy shells are filled with 8 electrons.
Sodium on its own has 11 electrons. Two of these are in the 1st energy level, eight in the 2nd energy level and one in the 3rd energy level. This arrangement is highly unstable rendering the element sodium highly unstable and reactive. It will burst into flames immediately on exposure to air and can burn through human flesh if it comes into contact with it.
Chlorine at room temperature is a poisonous gas. It has 17 electrons in the arrangement 2:8:7 . The outermost shell has 7 electrons and so this element is fairly stable but will readily react with human lungs with fatal consequences.
So each of these two elements on their own are deadly, but when the two react together, sodium gives up its single electron on the outer energy shell to chlorine which readily accepts it and fills its outer shell to make 8 forming ionic bonds and is thus the two are completely stable and cannot explode or react in any other way because the outer shell of each of them is now filled with 8 electrons.
Answer:
10.2 mg
Explanation:
Step 1: Calculate the total amount of water she drank
1 year has 365 days and she lived in Chicago for 2 years = 2 × 365 days = 730 days.
If she drank 1.4 L of water per day, the total amount of water she drank is:
730 day × 1.4 L/day = 1022 L
Step 2: Calculate the amount of Pb in 1022 L of water
The concentration of Pb is 10 ppb (10 μg/L).
1022 L × 10 μg/L = 10220 μg
Step 3: Convert 10220 μg to milligrams
We will use the conversion factor 1 mg = 1000 μg.
10220 μg × 1 mg/1000 μg = 10.2 mg
