You can determine the mass defect when you calculate for the absolute difference of the experimentally determined molar mass and the theoretical molar mass.
64Ni means there are 28 protons, 28 electrons and (64 - 28) = 36 neutrons. The mass of each proton is 1.0072766 amu; the mass of each electron is <span>0.00054 </span>amu; the mass of each neutron is <span>1.008664 amu.
Theoretical molar mass = 28(</span>1.0072766 amu) + 28(0.00054 amu) + 36(1.008664) = 64.5308 amu
Thus,
Mass defect = |63.9280 amu - 64.5308 amu| = <em>0.6028 amu</em>
Answer:
- g) 0.20 mol
- h) 2.0 mol/dm³
- i) 2.8 g
Explanation:
<h2>a) </h2>
1. Data:
2. Solution:
i) Formulae:
- number of moles = mass in grams/Ar
- number of atoms = number of moles × Avogadro constant
- Avogadro constant = 6.022 × 10²³ atoms/mol
ii) Calculations:
- number of moles = 71g / 35.5(g/mol) = 2 mol
- number of atoms = 2mol × 6.022 × 10²³ atoms/mol = 1.20 × 10²⁴ atoms
<h2>b) </h2>
1. Data:
- 0.2 mol KOH
- Ar: H = 1, O = 16, k = 39
2. Solution
i)Formula:
- mass = number of moles × molar mass
ii) Molar mass:
- 1×1g/mol + 1×39g/mol + 1×16g/mol = 56g/mol
iii) Calculations:
- mass = 0.2 mol × 56g/mol = 11.2 g/mol ≈ 10g/mol (rounded to 1 significant figure)
<h2>c) </h2>
1. Data:
2. Solution
i) Formula:
- number of moles = mass in grams / Ar
ii) Calculations:
- number of moles = 1.4g / 7 gmol = 0.7 mol
<h2>d) </h2>
1. Data:
2. Solution
i) Formula:
- mass = number of moles × molar mass
ii) Calculations:
- molar mass = 8 × 32g/mol = 256 g/mol
- mass = 4 mol × 256 g/mol = 1,024 g ≈ 1,000 g (rounded to 1 significant figure)
<h2>e)</h2>
1. Data:
- Mr: Ca(NO₃)₂ . 2H₂O = 200
2. Solution
i) Formulae:
- number of moles = mass in grams / molar mass
ii) Calculations:
- number of moles = 50 g / 200 g/mol = 0.25 mol of Ca(NO₃)₂ . 2H₂O
The number of moles of water molecules is 2 times the number of moles of Ca(NO₃)₂ . 2H₂O.
- number of moles of water molecules = 2 × 0.25 mol = 0.5 mol
<h2>f) </h2>
1. Data:
2. Solution:
i) Formulae:
- number of atoms = number of moles × Avogadro constant
- number of moles = mass in grams / molar mass
ii) Calculations
- number of moles = 4.9g / 98g/mol = 0.050 mol
- number of atoms = 0.050 mol × 6.022 × 10²³ atoms/mol = 3.0×10²² atoms
<h2>g) </h2>
1. Data:
- V = 24 dm³ (air)
- 20% oxygen
- r.t.p ⇒ T = 298K, p = 1 atm
2. Solution
i) Formula:
ii) Calculation:
- R = 0.08206 (atm.dm³/K.mol)
- n = [ 1 atm × 24 dm³] / (0.08206atm.dm³/K.mol × 298K) = 0.98mol of air
- moles of oxygen = 20% × 0.98 mol ≈ 0.20 mol
<h2>h) </h2>
1. Data:
2. Solution
i) Formula:
- Molarity = moles of solute / volume of solution in dm³
ii) Calculations:
25cm³ × (0.1cm/dm)³ = 0.125 dm³
- Molarity = 0.25 mol / 0.125 dm³ = 2.0 mol/dm³
<h2>i) </h2>
1. Data:
- V = 35cm³
- M = 2 mol/dm³
- Mr NaOH = 40
2. Solution
i) Formulae:
- number of moles = M × V (in dm³)
- mass = number of moles × mola rmass
ii) Calculations:
- V = 35cm³ × (0.1dm/cm)³ = 0.035dm³
- number of moles = 2 mol/dm³ × 0.035 dm³ = 0.070 mol
- mass = 0.070 mol × 40 g/mol = 2.8 g
Answer:
The Correct Answer is A and C.
Explanation:
- The wind is the movement of air, the movement of air is happened by the difference in pressure.
- A difference in air pressure is what causes the wind to blow. Difference in pressure is happened by the uneven heating of the earth's surface.
- The wind is normally moving air from a high air pressure place to a low air pressure place.
- The greater the difference in air pressure the stronger the wind blow.
Answer:
The absolute zero temperature T = - 269.91° C
Explanation:
From the given information:
The plot of the volume of the experimental data against the celsius temperature can be expressed mathematically as:
V = mT + c
V = 0.0741 × T+c --- (1)
where;
m, which is the straight line of the slope = 0.0741
replacing the value of V to be = 20 L, T= 0.
Then:
20 = 0.0741 × 0 + c
20 = c
From equation (1), replacing the value of c with 20, we have:
V = 0.0741 × T+20
SO, to determine absolute zero temperature: we have the volume to be zero at absolute zero temperature, Thus:
0 = 0.0741 × T+20
0.0741 T + 20 = 0
0.0741 T = - 20
T = - 269.91° C
Answer:
A
Explanation:
Acid chloride: --C=O-Cl. Stretch range ~1750-1820cm-1. I'd probably pick
(A) 1800 cm-1, as this value is in the middle (-ish) of that range.
Hence the correct answer is 1800 cm^-1
