Which of the following is correct? (A) The activation energy changes when temperature changes. (B) The Arrhenius equation only applies to 1st order reactions. (C) The rate constants at higher temperatures are ALWAYS larger than at low temperatures for the same chemical reaction. (D) The rates of reaction at higher temperatures are ALWAYS larger than at low temperatures for the same chemical reaction.

The decomposition of dimethyl ether (CH3OCH3) to methane, carbon monoxide, and hydrogen gases is found to be first-order. At 500°C, a 150.0−mg sample of dimethyl ether is reduced to 43.2mg after three quarters of an hour. Calculate(a) the rate constant.(b) the half-life at 500 °C.(c) how long it will take to decompose 95% of the dimethyl ether.

The activation energy for a certain first order reaction is 139 kJ/mol. If the rate constant is 0.282 s at 12.4°C, what will the rate constant for the reaction be if the temperature is doubled? 0.564 s1 0.283 s1 (A) (B) (C) (D) (E) 0.361 s1 0.553 s1 3.22 s1

Drug metabolism In order to be effective, a certain drug must be at amountgreater than 10 mgin the body.The drug is removed from the body with first-order kinetics and ahe half-life is 4.0 hr. (a) (6) If a patient is given a 100 mg dose at midnight, at what time should the patient take another dose such that the concentrationdoes not dip below 10 mg? (b) (4) You discover that the patient ate a grapefruit recently, which inhibits degradation of the drug, reducing the firstorder rate constant by 50%. If you want the drug to be effective for 24 hr(i.e., amount >10 mg), what dosage should you give the grapefruit-eating patient?