Delta Hf = dHf
<span>dHf rxn = (n*dHf products) - (n*dHf reactants). </span>
<span>Substitute 5113.3 kJ for dHf rxn and solve for the only unknown in the equation which is dHf C8H18.
</span>-5133.3-[(8x-393.5)+9(-241.8)] = 190.9
<span>Since it is an enthalpy of formation, the value has to be negative, </span>
<span>thus the correct answer is -190.9</span>
C = vf
c stands for the speed of waves (which is a constant that is 3 x 10^8)
v stands for the wavelength (which is given)
f stands for frequency (what we are solving for)
3 x 10^8 = (1.08 x 10^-6)f
Divide both sides by the given wavelength
f = 2.78 * 10^14 seconds
B. inference because she drew a conclusion based on evidence.
Because the evidence was that she heard the crashing sound, and then when she came into her room saw the broken window and baseball.
It was not an observation because she did not directly see the baseball going through the window
Of what type of solutions
like any type
<span>In order to determine the mass of the piece of copper with only knowing it's density, it must have it's volume measured. In order to do this, the piece of copper could be placed in a container filled to the brim with a spout and a graduated cylinder below the spout. Then the piece of copper can be placed into the container without any fingers in the water. Then water will displace into the cylinder, the measured volume is the volume of the piece of copper, because of Archimede's principle, and we assume that the water is 1.0 g/mL or 1 g/cm^3. Then multiply the density with the volume to get the mass of the piece of copper.</span>