Answer: v = 2π2 Kme2 Z / nh
Explanation:
The formula for velocity of an electron in the nth orbit is given as,
v = 2π2 Kme2 Z / nh
v = velocity
K = 1/(4πε0)
m= mass of an electron
e = Charge on an electron
Z= atomic number
h= Planck’s constant
n is a positive integer.
Answer:
A & B
Explanation:
Noble Gases are the least reactive as they have a full valence shell (and are stable)
Answer:
148 grams of relative atomic mass
Explanation:
magnesium atomic mass : 24
nitrogen : 14
oxygen : 16
24 × 1
14 × 1 × 2
16 × 3 × 2
24 + 28 + 80 = 148 grams
We get the pressure of the hydrogen gas from the difference between the measured pressure and the vapor pressure of water:
total pressure = Pressure of H2 + Vapor Pressure of H2O
1.00 atm = Pressure of H2 + 0.0313 atm
Pressure of H2 = 1.00 atm - 0.0313 atm = 0.9687 atm
From the ideal gas law,
PV = nRT
we can calculate for the number of moles of H2 as
n = PV/RT = (0.9687 atm)(0.246L) / (0.08206 L·atm/mol·K)(298.15 K)
= 0.00974 mol H2
where
V = 246 mL (1 L / 1000 mL) = 0.246 L
T = 25 degrees Celsius + 273.15 = 298.15 K
We use the mole ratio of Na and H2 from the reaction of sodium metal with water as shown in the equation
2Na(s) + 2H2O(l) → 2 NaOH(aq) + H2(g)
and the molar mass of sodium Na to get the mass of sodium used in the reaction:
mass of Na = 0.00974 mol H2 (2 mol Na /1 mol H2)(22.99 g Na/1 mol Na)
= 0.448 grams of sodium
To determine the amount of each solution that she should use, we do mass balance for the whole process. We let x be the amount the 65% salt and y the amount of the 90% salt. We do as follows:
The total mass should be equal to 150 oz.
x + y = 150
Doing a salt balance, we obtain the second equation:
.65x + .90y = 150(.85)
Solving for x and y, we obtain:
x = 30 oz
y = 120 oz
