Answer:
The ΔH of the reaction is + 12.45 KJ/mol
Explanation:
Mass of water= 100ml = 100g. (You should always assume 1cm3 of water as 1g)
heat capacity of water = 4.18 Jk-1 Mol-1
Change in temperature = (19.86 - 25.00) = -5.14 K (This is an endothermic reaction because of the fall in temperature)
Molar mass of NaHCO3 = 84 g/mol
Mole of NaHCO3 = 14.5 / 84 = 0.173 mol
Step 1 : Calculate the heat energy (Q) lost by the water.
Q = M x C x ΔT
Q = -100 x 4.18 x (-5.14)
Q = 2148.5 joules
Q = 2.1485 K J
Step 2: Calculating the ΔH of the reaction?
ΔH = Q / number of moles of NaHCO3
ΔH = 2.1485 / 0.173
ΔH = 12.42 KJ/mol
Answer:
The speed of the particle at x = 4.0 m is 13.66 m/s
Explanation:
The work done by this force between the two points above is given by
W = ∫ F dx
W = ∫⁴₋₄ (-5x² + 7x) dx
W = [(-5x³/3) + (7x²/2)]⁴₋₄
W = [(-5(4³)/3) + (7(4²)/2)] - [(-5(-4)³)/3) + (7((-4)²)/2)] = (-50.6667) - (162.6667) = (- 213.33 J)
Kinetic energy at -4.0 m
At this point, v = 20 m/s
K.E = mv²/2 = 2 × 20²/2 = 400 J
To obtain the kinetic energy at 4 m,
We apply the work-energy theorem which mathematically translates to
The work done in moving a particle from one point to another = Change in kinetic energy of the particle between those two points
W = ΔK.E
Work done between x = - 4m and x = 4 m is - 213.33 J
Hence, ΔK.E = -213.33 J
Change in kinetic energy of the particle between x = - 4m and x = 4m is ΔK.E
ΔK.E = (Kinetic energy at x = 4m) - (kinetic energy at x = - 4m)
- 213.33 J = (mv²/2) - 400
mv²/2 = -213.33 + 400 = 186.67 J
2v² = 2 × 186.67
v² = 186.67
v = 13.66 m/s.
Answer:
MgSO4.7H2O
Explanation:
Let the formula for the hydrated magnesium sulphate be MgSO4.xH2O
Mass of the hydrated salt (MgSO4.xH2O) = 12.845g
Mass of anhydrous salt (MgSO4) = 6.273g
Mass of water molecule(xH2O) = Mass of the hydrated salt — Mass of anhydrous salt = 12.845 — 6.273 = 6.572g
Now,we can obtain the number of mole of water molecule present in the hydrated salt as follows:
Molar Mass of hydrated salt (MgSO4.xH2O) = 24 + 32 + (16x4) + x(2 + 16) = 24 + 32 + 64 + x(18) = 120 + 18x
Mass of xH2O/ Molar Mass of MgSO4.xH2O = Mass of water / mass of hydrated salt
18x/120 + 18x = 6.572/12.845
Cross multiply to express in linear form
18x x 12.845 = 6.572(120 + 18x)
231.21x = 788.64 + 118.296x
Collect like terms
231.21x — 118.296x = 788.64
112.914x = 788.64
Divide both side by 112.914
x = 788.64 /112.914
x = 7
Therefore the formula for the hydrated salt (MgSO4.xH2O) is MgSO4.7H2O
Reactants left products right
- According to Pascal’s principle, for a certain fluid in a totally enclosed system, a change in pressure at a given point in the fluid is transferred to all points in the fluid, as well as to the enclosing walls.
- This is illustrated by the fact that the pressure inside an enclosed system is the same according to the relation [ pressure = force/area ]. Therefore, the change in pressure resulting from squeezing a ketchup bottle will be transferred equally to all parts of that bottle as well as its internal content.
- That’s how hydraulic machines, such as garbage trucks and hydraulic lifts function..
