How much power was used by a cyclist when it took them 2.5 hours to finish their race. The cyclist exerted a force of 32N and the race was 75km long. Must convert km to m prior to calculations. Must show all work, have correct sig figs, and include correct units for full credit.

Explanation:

Given:

Force, f = 32 N

Distance, d = 75 km

1 km = 1,000 m

75 km × 1000 m/1 km

= 75,000 m

Time, t = 2.5 hours

60 secs = 1 min

60 mins = 1 hour

2.5 hours × 60 mins/ 1 hour × 60 sec/1 min

= 9,000 secs

Power = energy/time

Energy = force × distance

Power = (32 × 75,000)/9,000

= 266.67 W

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.