Answer:
1.133 kPa is the average pressure exerted by the molecules on the walls of the container.
Explanation:
Side of the cubic box = s = 20.0 cm
Volume of the box ,V= 

Root mean square speed of the of helium molecule : 200m/s
The formula used for root mean square speed is:

where,
= root mean square speed
k = Boltzmann’s constant = 
T = temperature = 370 K
M = mass helium = 
= Avogadro’s number = 

Moles of helium gas = n
Number of helium molecules = N =
N = 
Ideal gas equation:
PV = nRT
Substitution of values of T and n from above :






(1 Pa = 0.001 kPa)
1.133 kPa is the average pressure exerted by the molecules on the walls of the container.
Answer:
No of Moles in excess at the end of the reaction is 0.25 moles
Explanation:
AgNO3 + Mg3P2 → Ag3P + Mg(NO3)2
Balancing the equation we get
6AgNO3 + Mg3P2 → 2Ag3P + 3Mg(NO3)2
6 moles of AgNO3 needs 1 mole of Mg3P2
using unitary method
AgNO3 = 
1.5 AgNO3 =
= 1/4 = 0.25moles of Mg3P2
So 1.5 Moles of AgNO3 requires 0.25Mg3P2 for complete reaction but we have 0.5Moles of Mg3P2 available Therefore Mg3P2 is in excess
No of Moles in excess at the end of the reaction = 0.5 - 0.25 = 0.25moles
<span>We can use the heat
equation,
Q = mcΔT </span>
<span>
Where Q is the amount of energy transferred (J), m is
the mass of the substance (kg), c is the specific heat (J g</span>⁻¹ °C⁻<span>¹) and ΔT is the temperature
difference (°C).</span>
According to the given data,
Q = 300 J
m = 267 g
<span>
c = ?
ΔT = 12 °C</span>
By applying the
formula,
<span>300 J = 267 g x c x
12 °C
c = 0.0936 J g</span>⁻¹ °C⁻<span>¹
Hence, specific heat of the given substance is </span>0.0936 J g⁻¹ °C⁻¹.
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