A device for determining, firstly, a thermal conductivity and/or the specific thermal capacity of a gas mixture and, secondly, a density and/or a viscosity of the gas mixture, comprising: a chip prepared from a semiconductor wafer, in particular an SOI wafer (10; 110), with at least a first cantilever that can oscillate (20; 120) with a first piezoelectric converter (30; 130) which is used to initiate an oscillation of the cantilever (20; 120) with a first frequency, wherein the chip (10; 110) has a recess (11; 111) into which a free end section of the first cantilever that can oscillate projects; at least a first temperature sensor element with a temperature-dependent resistance value for detecting a temperature of the gas mixture; at least a second temperature sensor element with a temperature-dependent resistance value for detecting a temperature of the gas mixture; at least a first heating element; and an evaluation and/or calculation unit which is configured to determine the density and viscosity of the gas mixture based on the oscillation properties of the at least one cantilever (20; 120), and to determine the thermal conductivity and/or the specific thermal capacity of the gas mixture based on measured temperature values of the first temperature sensor element and the second temperature sensor element (50; 150, 240), as well as the power consumption of the heating element; characterized in that the first temperature sensor element is formed in the free end section of the first cantilever, the second temperature sensor element is positioned at a distance from the first cantilever (20; 120), the first heating element is formed in the free end section of the cantilever (20; 120), and at least one section of the recess (11; 111) extends between the first heating element and the second temperature sensor element (50; 150, 240). a chip prepared from a semiconductor wafer, in particular an SOI wafer (10; 110), with at least a first cantilever that can oscillate (20; 120) with a first piezoelectric converter (30; 130) which is used to initiate an oscillation of the cantilever (20; 120) with a first frequency, wherein the chip (10; 110) has a recess (11; 111) into which a free end section of the first cantilever that can oscillate projects; at least a first temperature sensor element with a temperature-dependent resistance value for detecting a temperature of the gas mixture; at least a second temperature sensor element with a temperature-dependent resistance value for detecting a temperature of the gas mixture; at least a first heating element; and an evaluation and/or calculation unit which is configured to determine the density and viscosity of the gas mixture based on the oscillation properties of the at least one cantilever (20; 120), and to determine the thermal conductivity and/or the specific thermal capacity of the gas mixture based on measured temperature values of the first temperature sensor element and the second temperature sensor element (50; 150, 240), as well as the power consumption of the heating element; characterized in that the first temperature sensor element is formed in the free end section of the first cantilever, the second temperature sensor element is positioned at a distance from the first cantilever (20; 120), the first heating element is formed in the free end section of the cantilever (20; 120), and at least one section of the recess (11; 111) extends between the first heating element and the second temperature sensor element (50; 150, 240).