explain ..-11 points SerpSE9 19 P 011 MI FB My Notes O As Y My Notes Ask Your T

Question

explain

..-11 points SerpSE9 19 P 011 MI FB My Notes O As Y My Notes Ask Your T A copper telephone wire has essentially no sag between poles 34.0 m apart on a winter day when the temperature is 20.0°C. How for use in solving this prablem.) much longer is the wire on a summer day when the temperature is 30.0 C? (Note: Table 19.1 is available Need Help? eMastse -1 points SerPSE9 19 P 036 WI My Notes Ask Your Te In state-of-the-art vacuum systems, pressures as low as 1.00 x 10° Pa are being attained. Calculate the number of molecules in a 1.40-m2 vessel at this pressure and a temperature of 30.0°c. molecules Need Help? dWaich

Explanation / Answer

given

initial length, L1 = 34 m

T1 = -20 C

T2 = 30 C

coefficient of linera expansion of copper, alfa = 17*10^-6 C^-1

final length, L2 = ?

we know, delta_L = L1*alfa*(T2-T1)

delta_L = L1*alfa*(T2-T1)

= 34*17*10^-6*(30-(-20))

= 0.0289 m

= 2.89 cm

===============================

given

P = 1*10^-9 pa

V = 1.4 m^3

T = 30 C

= 30 + 273

= 303 K

let n is the no of oles of the gas.

use ideal gas equation

P*V = n*R*T

==> n = P*V/(R*T)

= 1*10^-9*1.4/(8.314*303)

= 5.557*10^-13 mol

we know, no of moleculed, N = n*NA (here NA is avagadro's number)

= 5.557*10^-13*6.023*10^23

= 3.345*10^11

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