# Final temperature | Science homework help

An unknown mass of each of the following substances, initially at 24.0°C, absorbs 1930J of heat. The final temperature is recorded as indicated. Find the mass of each substance.

a. Pyrex glass (Tf=55.1°C)
m=____________g

b.sand (Tf=62.1°C)
m=____________g

ethanol (Tf=44.0°C)

water (Tf=32.0°C)

m=___________g

A 32.9g iron rod, initially at 21.9°C, is submerged into an unknown mass of water at 62.9°C, in an insulated container. The final temperature of the mixture upon reaching thermal equilibrium is 59.6°C.

What is the mass of the water?
Express your answer to two significant figures and include the appropriate units.
m=
m=____________g

Consider the following generic reaction: A+2B?C+3D, ?H = 101kJ . Determine the value of ?H for each of the following related reactions:

a. 3A+6B?3C+9D
?H = kJ

b. C+3D?A+2B
?H = kJ

c. 1/2C+3/2D?1/2A+B
?H = kJ

Calculate the wavelength of each of the following frequencies of electromagnetic radiation.

?1 = m

?1 = m

835.6 MHz (common frequency used for cell phone communication)

?3 = m

A heat lamp produces 23.0 watts of power at a wavelength of 6.7µm .

How many photons are emitted per second? (1 watt = 1 J/s)

N = s-1

Calculate the de Broglie wavelength (in pm) of a hydrogen atom traveling 445m/s .

? =

An electron traveling at 2.6×105m/s has an uncertainty in its velocity of 9.25×104m/s .

What is the uncertainty in its position?