Speeds of sound in (0.95 N2 + 0.05 CO and 0.9 N2 + 0.1 CO) gas mixtures at T = (273 and 325) K and pressure up to 10 MPa

• Experimental speeds of sound for two mixtures are reported.
• A spherical resonator is used for the measurements.
• Heat capacities are calculated from the speeds of sound.

The measurements of speed of sound for two mixtures of (N2 + CO) are reported. The data have been obtained using a spherical resonator for two isotherms T = (273.15 and 325.15) K and pressures up to 10 MPa. The uncertainty study is detailed and the total uncertainty of the speed of sound is not worse than 0.016%. The results have been compared with the GERG-2008 equation of state.