The 21st century student learns and communicates in the virtual world. In order to meet the individual instructional needs of the students, virtual science laboratories should be researched to accomplish the goal. This study evaluated the effectiveness of a virtual chemistry laboratory in enhancing students' conceptual understanding as a pre-laboratory assignment. The study included thirteen undergraduate science majors enrolled in a second semester general chemistry laboratory course. Two experiments were selected from the syllabus to be performed virtually, in addition to the physical laboratory. The Chemistry Assessment Test in Kinetics (CATK) was developed and administered as a pre- and post-assessment tool to determine if conceptual understanding had taken place. The difference in results of the paired samples t-test was significant from the pre- and post-CATK which indicated that the students' conceptual understanding increased after completing the virtual chemistry laboratory. The results also determined that the male students outperformed their female counterparts on the CATK.