The heat for melting or freezing water, also called the Heat of Fusion (Hf), is 80 calories per gram at 0Â°C, which is the equilibrium temperature. In other words, it is necessary to add 80 calories of energy to melt one gram of ice at 0Â°C.
The CVV Number (Card Verification Value) on your credit card or debit card is a 3 digit number on VISAÂ®, MasterCardÂ® and DiscoverÂ® branded credit and debit cards. On your American ExpressÂ® branded credit or debit card it is a 4 digit numeric code.
Contact phone numbers for American Express customer service are available 24 hours a day, 7 days a week. 1  Customer Service: 1-800-528-4800. 2  TTY / TDD: 1-800-221-9950. 3  TTY / TDD (New York): 1-800-522-1897.  Pay Your Bill by Phone: 1-800-472- 1 9297. Apply for American Express Credit: 1-800-223-2670.  Express Cash Customer Service: 1-877-297-4438.