Composition containing cis-1,2-difluoroethylene

A composition comprising cis-1,2-difluoroethylene (HFO-1132(Z)), wherein the composition comprises cis-1,2-difluoroethylene (HFO-1132(Z)) and an additional compound, the additional compound being at least one member selected from the group consisting of trans-1,2-difluoroethylene (HFO-1132(E)), 1-chloro-1,1,2-trifluoroethane (HCFC-133), 2-chloro-1,1,1-trifluoroethane (HCFC-133b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), 1,1-difluoroethane (HFC-152a), 1,2-difluoroethane (HFC-152), fluoroethane (HFC-161), 1,1,1-trifluoroethane (HFC-143a), 1,1,2-trifluoroethane (HFC-143), 1,1,1,2-tetrafluoroethane (HFC-134a), difluoromethane (HFC-32), pentafluoroethane (HFC-125), fluoromethane (HFC-41), chlorodifluoromethane (HCFC-22), ethylene, propylene, acetylene, 1-chloro-1,2-difluoroethane (HCFC-142a), 3,3,3-trifluoropropene (HFO-1243zf), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,1,2-trifluoroethylene (HFO-1123), fluoroethylene (HFO-1141), 1,1-difluoroethylene (HFO-1132a), 1-chloro-2,2-difluoroethylene (HCFO-1122), and 1-chloro-1,2-difluoroethylene (HCFO-1122a), and

• wherein the composition comprises the additional compound in a total amount of less than 1 mass % 0.1 mass % or less based on the total amount of the HFO-1132(Z) and the additional compound, defined as 100 mass %.