Methane molar mass

Eleven elements are gases under normal conditions (Fig. 4.2). So are many compounds with low molar masses, such as carbon dioxide, hydrogen chloride, and organic compounds such as the methane, CH4, of natural gas and the... 

If the sample consists of atoms of one element, the mass spectrum gives the isotopic distribution of the sample. The relative molar masses of the isotopes can be determined by comparison with atoms of carbon-12. If the sample is a compound, the formula and structure of the compound can be determined by studying the fragments. For example, the + 1 ions that CH4 could produce are CH4, CH3+, CH, CFI4, C+, and H4. Some of the particles that strike the detector are those that result when the molecule simply loses an electron (for example, to produce Cl I4+ from methane) ... 

Use the molar mass of methane to calculate the number of moles ... 

A gas turbine with power output of 10.7 MW and an efficiency of 32.5% burns natural gas. In order to reduce the NOx emissions to the environmental limits, 0.6 kg steam is injected into the combustion per kg of fuel. The airflow through the gas turbine is 41.6 kg-s 1. The composition of the natural gas can be assumed to be effectively 100% methane with a molar mass of 16 kg-kmoU1. The kilogram molecular volume can be assumed to occupy 22.4 m3 at standard conditions. 

Hydrogenolysis of 2-methylpentane, hexane, and methylcyclopentane has been also studied on tungsten carbide, WC, a highly absorptive catalyst, at 150-350 °C in a flow reactor [80], These reforming reactions were mainly cracking reactions leading to lower molar mass hydrocarbons. At the highest temperature (350 °C) all the carbon-carbon bonds were broken, and only methane was formed. At lower temperatures (150-200 °C) product molecules contained several carbon atoms. 

B—Lighter gases effuse faster. The only gas among the choices that is lighter than methane is helium. To calculate the molar mass, you would begin with the molar mass of methane and divide by the rate difference squared ... 

Use the formulas of methane, ethane, and propane to calculate the compounds molar masses. 

Suppose that your burner gas contains a small amount of ethane (C2H6). How will the presence of this compound affect your calculated molar mass if the burner gas is predominantly a. methane... 

Drawing a Conclusion How does your experimental molar mass compare with the molar masses of methane, ethane, and propane Suggest which of these gases are in the burner gas in your laboratory. 

Illustrative Example 18.2 Estimating Molecular Diffusivity in Air Problem Estimate the molecular diffusion coefficient in air, >,a, ofCFC-12 (see Illustrative Example 18.1) at 25°C (a) from the mean molecular velocity and the mean free path, (b) from the molar mass, (c) from the molar volume, (d) from the combined molar mass and molar volume relationship by Fuller (Eq. 18-44), (e) from the molecular diffusivity of methane. 

Fig. 8. Copolymer separation. Gradient elution of the mixture of three poly(styrene-c -methyl acrylate) samples on a silica column (600 x 7.5 mm do = 5nm dp= 15 pm). Gradient tetrachloro-methane/methyl acetate (7-35% B in 35 min) flow rate 1 ml/min. The figures at the peaks indicate the composition of the respective copolymer in mol % methyl acrylate. Molar mass values 46.6 — 261 kg/mol 57.3 — 276 77.9 — 302. (From Ref. 381 with permission)...

We already know how to use the molar mass of methane (16.04 g-mol-1) to work out the number of moles of CH4 corresponding to 150 g. From these relations, we can write... 

For example, how much faster does helium effuse than methane The molar mass of helium and methane are 4 g/mol and 16 g/mol, respectively. If we insert these values into Graham s law, we find helium effuses at twice the rate of methane. 

It might be instructive to consider the impact of molar mass on the physical properties of a regular series of saturated organic hydrocarbons, called a homologous series. Let s start with the simplest member, methane, CH4, and, on papery sequentially add one CH2 unit (or methylene group) to build the series. To start, consider writing methane as CH3-H, and then insert CH2 into the bond between the CH3 and the H. The result is ethane, CH3-CH2-... 

The correct answer is (A). There is a quick way to solve this and also a long way. The quick way is to remember that Graham s law states that the rate of effusion is inversely proportional to the square root of the molar mass. You can see pretty quickly that the molar mass of methane is 4 times that of helium. The square root of 4 is 2, meaning that helium will diffuse two times faster than methane. The longer way is to actually set up the equation — = and solve for r2. 

It readily follows from Eq. 3.2 that the translational kinetic energy of a gas is independent of the volume (or pressure), the molar mass or the nature of the gas. It depends only on temperature (T). Thus, a hydrogen molecule has the same average translational kinetic energy as a molecule of nitrogen, ammonia or methane. The molecular velocity, of course, would be different in each gas. 

Since the number 16.043 represents the mass of 1 mole of methane molecules, it makes sense to call it the molar mass for methane. However, tradi-A substance s molar mass (molecular tionally, the term molecular weight has been used to describe the mass of 1 weight) is the mass in grams of mole of a substance. Thus the terms molar mass and molecular weight mean... 

Use atomic masses and numbers of each type of atom to determine molecular mass for methane. Express that molecular mass in grams per mole to determine molar mass. 

Divide the mass in grams of methane by its molar mass to find the number of moles. 

Methane (CH4) effuses through a small opening in the side of a container at the rate of 1.30 X 10 mol s h An unknown gas effuses through the same opening at the rate of 5.42 X 10 mol when maintained at the same temperature and pressure as the methane. Determine the molar mass of the unknown gas. 

Find the temperature change of the water, using the equation 7" = Tfinai - Tinitiai- Then, use the equation = (m)(AT)(Q). The negative of the value of fll equal reaction for the burning of 1.60 g of methane. Use the molar mass of methane, 16.0 g methane/1.0 mol methane, as a conversion factor to find the ( reaction for 1-0 mol of methane. 

Now, use a molar-mass conversion factor to find < reaction> or AH, for 1 mol of methane. 

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