What is a physical change?

Write the balanced equation for a reaction between aqueous nitric acid (hno3) and solid lithium metal (this is a single replacement reaction)

The lattice enthalpy (formation of ionic solid from ions in the gas phase) for agcl(s) is -916 kj/mol and the hydration enthalpy (dissolution of gaseous ions into water) is -850 kj/mol. how much heat (in joules) is involved in forming 1l of saturated agcl solution (1.8 × 10-4 g / 100 ml water) by dissolving agcl(s)? assume solution volume does not change much upon dissolution. the equations are given below. ag+(g) + cl−(g) æ agcl(s)

Reactions in cells take place at about a. 40°c b. 0° c. 100°c d. 60°c