I'm not sure where you are getting your information. Chimpanzees have 24 pairs of chromosomes and humans have 23 pairs. And what happened is that two of the chromosomes fused into one chromosome. Our chromosome two is essentially two of the chimp chromosomes (2p and 2q) stuck together. http://www.gate.net/~rwms/hum_ape_chrom.html has a pretty good picture of the chromosome two and its ape versions.