A 1.20g +/- 0.01g sample of hydrated MgCO3 is heated to drive of the water. The dry sample has a mass of 0.58g +/- 0.01g.

Does the number of ions in solution increase, decrease, or remain constant? it continuously decreases. it continuously increases. it decreases at first, then increases. it increases at first, then decreases.

At a certain temperature the rate of this reaction is first order in hi with a rate constant of : 0.0632s2hig=h2g+i2g suppose a vessel contains hi at a concentration of 1.28m . calculate how long it takes for the concentration of hi to decrease to 17.0% of its initial value. you may assume no other reaction is important. round your answer to 2 significant digits.

Use the drop-down menus to label each of the following changes p for physical change and c for chemical change. the substance changes to a new substance. the original substance can be recovered. the color changes. gas is produced and given off. the substance changes size, shape, or volume.