# PhySyCalc Tutorial

PhySyCalc is a calculator to help students in the physical sciences get the right answer faster. Have you ever been faced with a problem like this on an exam:

What pressure in atmospheres does 0.078 moles of hydrogen exert on the walls of a 42.0 mL container at 25.0 °C?

If you're clever you already know that you need to use the ideal gas equation of state,

pV = nRT.

So, you identify the variables

n is the # of moles = 0.078 mol
T is the temperature in Kelvin = 273.15 K+25.0 K = 298.15 K
V is the volume = 42.0 mL
R is the gas constant = 8.314510 J/(K • mol)

and know that you can get the pressure using p = nRT/V. You pull out your calculator and plug in the numbers

0.078 * 8.314510 * 298.15 / 42.0 = 4.60380357635714

and write down 4.6 on the exam. Time to move on to the next problem, right? Not so fast: don't you need units on that number? Oh yeah, the question asked for the pressure in atmospheres. So, it's 4.6 atmospheres, right? Guess again! Maybe you should write out the calculation on paper with units:

0.078 mol * 8.314510 J/(K*mol) * 298.15 K / 42.0 mL

Rats! Now you have to do two calculations. Do the number calculation on the calculator (and get 4.6), and work out the final units calculation by hand on paper.

mol * J/(K • mol) * K / mL = J/(mol * mL)

OK, the answer is 4.6 J/(mol * mL). But wait, you need the answer in atmospheres! Gosh, this seems like a lot more work than it needs to be.

We agree!

With PhySyCalc you can enter the entire calulation with numbers and units and get the numerical answer with the correct units. Try it. And there is the answer with the correct units. Wait! You need the answer in atmospheres. No problem. Simply right-click (or control-click) the mouse and up pops a menu of all possible units.  To help you save even more time we've added some fundamental physical constants so you don't have to always keep looking them up. For example, instead of typing in the full gas constant with units you can use the symbol R. Additionally you can get the answer directly in the desired unit by appending two dots followed by the desired unit. Fundamental constants:

 Constant Shortcut π π alpha particle mass m_a alpha particle mass energy m_a•c_0^2 atomic unit of charge density l_p Avogadro Constant N_A Planck Constant h_P Planck Constant/2 π &hbar Planck length l_p Planck time t_p Boltzmann Constant k_B Faraday Constant &F speed of light c_0 Acceleration due to gravity (at sea level) g_0 electron charge q_e nuclear magneton µ_N bohr magneton µ_B electron mass m_e proton mass m_p Gas Constant R neutron mass m_n electron magnetic dipole moment µ_e proton magnetic dipole moment µ_p neutron magnetic dipole moment µ_n electric constant ε_0 magnetic constant µ_0 conductance quantum G_0 magnetic quantum flux Φ_0 Fine Structure Constant α Rydberg Energy Ry Rydberg Constant R_H Stefan-Boltzmann Constant σ formula weight fw[Chemical Formula] atomic weight aw[Element Symbol] isotope weight aw[Isotope Symbol] isotope abundance abundance[Isotope Symbol] isotope nuclear spin spin[Isotope Symbol] isotope nuclear magnetic moment µ_I[Isotope Symbol] isotope nuclear electric quadrupole moment Q_I[Isotope Symbol] isotope nuclear gyromagnetic ratio γ_I[Isotope Symbol]

Notice, there is a shortcut for the atomic weight of any element or isotope in the periodic table using the element symbol. For example, you can get the atomic weight of carbon with aw[C], then calculate the grams of carbon in 3 moles by entering

aw[C] * 3 mol

If you need the mass of 16O isotope you can use

aw[O16]

If you need the natural abundance of 10B use

abundance[B10]

If you have any other fundamental physical constants you'd like us to add drop us a line, we'd love to hear from you.