Well if you go to Quiz-let it gives the answer the mass of a mole of compound is determined by adding the atomic masses of the atoms making up the molecules
The answer would be 371 because it has multiple complete digits
Answer:
a)Atomic number
Explanation:
Element symbol signifies the element. For eg, Na is sodium. Mass number is the sum of protons and neutrons of an atom of an element. Atomic mass is the molar mass of the given element. Finally, atomic number is unique to each element because it signifies the number of protons of that element. EACH ELEMENT has their UNIQUE number of protons. For eg, atomic number of hydrogen is 1 because it has 1 proton, NO OTHER ELEMENT HAS ATOMIC NUMBER 1 because NO OTHER ELEMENT HAS 1 proton.
Answer:
1.78 × 10²⁶ Atoms
Explanation:
Relation between number of molecules and moles is,
No. of Molecules = Moles × 6.022 × 10²³ Molecules/mol
No. of Molecules = 99 mol × 6.022 × 10²³ Molecules/mol
No. of Molecules = 5.96 × 10²⁵ Molecules
Also, In CO₂ Molecule there are 3 atoms.
So,
No. of atoms = 5.96 × 10²⁵ Molecules × 3
No. of atoms = 1.78 × 10²⁶ Atoms
a) The reaction is exothermic since the overall enthalpy change is negative. this means that the system has lost energy to the environment, namely, the apparatus and due to drought.
b) We first calculate the number of moles in 3.55 grams of magnesium.
number of moles= mass/ atomic mass
=3.55/24
=0.1479 moles(to 4sf)
now, if 2 moles of magnesium give -1204kJ
How much energy is given by 0.1479 moles
= (0.1479×-1204kJ)
=-89.0358kJ (don't forget the negative sign)
c) two molesof MgO produces -1204kJ of energy
then -234kJ will be produced by
=(-234kJ×2moles)/1204kJ
=0.3887moles
one mole of MgO weighs 24+16=40
therefore the mass produced is 0.3887moles×40=15.548grams
(d) we first find the number of moles of MgO in 40.3 grams
number of moles=mass/RFM
=40.3g/40= 1.0075moles
if 2 moles of MgO give 1204 kJ then decomposing 1.0075 moles requires
(1.0075 moles×1204kJ)/2=606.515kJ
