1) how many grams of co are needed to react with an excess of fe2o3 to produce 225.5 gfe? numbers after symbols are subscripts unless there is a ^ to show it is an exponent. fe2o3(s) +3co(g) -- > 3 co2(g) + 2 fe(s)

2) solid sodium reacts violently with water producing heat, hydrogen gas and sodium hydroxide. how many molecules of hydrogen gas are produced when 65.4 g of sodium are added to water? numbers after symbols are subscripts unless there is a ^ to show it is an exponent. 2 na(s) +2 h2o(l) -- > 2 naoh(aq) + h2(g)

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

- lead + phosphoric acid = hydrogen + lead(ii) phosphate