Consider the intermediate chemical reactions.
ca(s) + co2(g) + o2(g) - cacos(s) ah, = -812.8 kj
2 ca(s)+ o2(g) → 2cao(s)
ah, = - 1,269.8kj
the final overall chemical equation is cao(s) + co2(g) → caco3(s). when the enthalpy of this overall chemical equation is
calculated, the enthalpy of the second intermediate equation
is halved and has its sign changed.
is halved.
has its sign changed.
is unchanged.

Name the element in group 17, period 2. (periodic table)

What is the relationship between wind and ocean waves? question 17 options: wind moving at higher speeds will transfer more energy to the water, resulting in stronger waves. wind moving at higher speeds will transfer energy over a larger part of the ocean water, resulting in waves with a shorter wavelength. winds moving at higher speeds with cause water to move forward at faster rates, causing larger ocean waves. winds moving at higher speeds will affect deeper water, resulting in waves that move at a faster rate. how do temperature and salinity affect deepwater currents? question 15 options: as temperatures and salinity levels of water increase, the water rises to the surface where it creates currents as it moves to colder regions. they create changes in wind direction, moving denser water in the same direction as the wind and causing the deepwater circulation patterns found in the ocean. they equalize the forces on undersea currents caused by the coriolis effect as they replace more dense water with less dense water. they create density differences that cause dense deepwater currents to flow toward the equator where they displace less dense, warmer water above them.

An alloy contains 66 g of pure zinc. what is the percentage of zinc in the alloy? express your answer to two significant figures and include the appropriate units.