Answer:
the number of molecules in 7g nitrogen
Ans) 7 gram of Nitrogen contains 1.5×10^23 molecules =1.5e+23
Answer:
C. A physical change.
Explanation:
A liquid is cooled during an investigation causing it solidify.Which of the following most likely occurred?
A. Absorption of heat. NO. Heat was released.
B. A chemical change. NO. It was a physical change
C. A physical change. YES. The physical change is called solidification.
D. Formation of a new compound. NO. This would be a chemical change.
Answer:
Common environmental chemical pollutants include pesticides and herbicides, volatile organics (VOCs) such as benzene, toluene; and chloroform, heavy metals such as lead, mercury, and arsenic; air contaminants such as carbon monoxide, ozone, particulate matter (PM), and second hand smoke; and persistent organic pollutants, such as the dioxins, PCBs, and DDT. Environmental chemicals can cause a broad spectrum of effects, which depend not only on route of exposure and dose, but on the susceptibility of the recipient of the pollution
The heat of combustion for methanol is 727 kj/mol
<em><u>calculation</u></em>
calculate the moles of methanol (CH3OH)
moles = mass/molar mass
molar mass of methanol = 12 +( 1 x3) +16 + 1= 32 g /mol
moles is therefore= 64.0 g / 32 g/mol = 2 moles
Heat of combustion is therefore = 1454 Kj / 2 moles = 727 Kj/mol
