I only need the last question at bottom of page answered. I know the first quest
ID: 105001 • Letter: I
Question
I only need the last question at bottom of page answered. I know the first question. It is just part of this whole series of questions so i posted the whole page for relevence and it was on there. I do NOT need to know the root mean square speed of N2 or H2, as I have them. Thank you kindly for your time!!!!
PSS 18.2: Kinetic-Molecular Theory Learning Goal: To practice Problem-Solving Strategy 18.2 Kinetic-molecular theory
At what temperature is the root-mean-square speed of nitrogen molecules equal to the root-mean-square speed of hydrogen molecules at 20.0 C? The molar mass of a nitrogen atom is 14.0 g/mol and the molar mass of a hydrogen atom is 1.01 g/mol.
Problem-Solving Strategy 18.2: Kinetic-molecular theory
IDENTIFY the relevant concepts: Use the results of the kinetic-molecular model whenever you are asked to relate macroscopic properties of a gas, such as temperature and pressure, to microscopic properties, such as molecular speeds.
SET UP the problem using the following steps: Identify which variables are known and which are the unknown target variables. Choose the equation(s) to be used from among Ktr=3/2nRT 1/2m(v^2)av=3/2kT vrms=(v^2)av=(3RT/M)=(3kT/m)
EXECUTE the solution as follows: The usual units for molar mass M are grams per mole; for example, the molar mass of oxygen is 32 g/mol. These units are often omitted in tables. When you use SI units in equations, such as the equations above, you must express M in kilograms per mole by multiplying the value shown in the table by the ratio 1kg/10^3g. Thus, in SI units, M for oxygen is 32×10^3kg/mol. Determine whether you are working on a "per molecule" basis or a "per mole" basis. Keep in mind that m is the mass of a molecule and M is the mass of a mole; N is the number of molecules, and n is the number of moles; k is the gas constant per molecule, and R is the gas constant per mole. Remember that T must always be in kelvins.
EVALUTE your answer: Keep in mind that typical molecular speeds at room temperature are several hundred meters per second. If your answer seems dramatically different, recheck your calculations.
IDENTIFY the relevant concepts Use the results of the kinetic-molecular model to compare the molecular speed of nitrogen and hydrogen gas molecules to their temperature.
SET UP
Part A
Below is a list of some of the relevant quantities in this problem; Subscripts H2 and N2 refer to the hydrogen and nitrogen molecules, respectively. Which of the following quantities are known? Check all that apply.
(vrms)N2
(vrms)H2
(M)N2
(T)H2
(m)N2
(Ktr)H2
(Ktr)N2
(T)N2
(M)H2
(m)H2
Explanation / Answer
Hi in chemical reactions we always use per mole basis only not per molecule. Because rms velocity depends on temperature (T). This in turns dependency of ktr also on tempearature since Ktr=3/2nRT 1/2m(v^2)av=3/2kT vrms=?(v^2)av=?(3RT/M)=?(3kT/m).
Hence we can rule out (vrms), (Ktr) and (T).
We left with molar mass (M) and mass of a molecule (m). Two of these quantities are known. molar mass of oxygen is 32 g/mol and 1mol of any substance posses 6.023 x 1023 molecules or formula units, also called as Avagadro's number(NA).
Therefore our answer to the question is as follows
M)H2,
M)N2,
T)H2
molar mass never changes in chemical reactions.Since H2 & N2 are non-radioactive.
Thank You So Much! Please Rate this answer as you wish.