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,

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.

Select "atmospheres" and there is your answer.

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 ^{16}O isotope you can use

`aw[O16]`

If you need the natural abundance of ^{10}B 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.