Answer:
When CO2 is breathed into the lungs, it dissolves in the water there, diffuses across the alveolar-capillary membrane, and enters the bloodstream. As it combines with water, it forms carbonic acid, making the blood acidic. So CO2 in the bloodstream lowers the blood pH.
 
        
                    
             
        
        
        
By multiplying the rate constant by the substrate concentration (amount) or by determining reaction velocity (V).