Tin(II) chloride dihydrate is also three-coordinate, with one water coordinated on to the tin, and a second water coordinated to the first. The main part of the molecule stacks into double layers in the crystal lattice, with the "second" water sandwiched between the layers. Tin(II) chloride can dissolve in less than its own mass of water without apparent decomposition, but as the solution is diluted, hydrolysis occurs to form an insoluble basic salt: Therefore, if clear solutions of tin(II) chloride are to be used, it must be dissolved in hydrochloric acid (typically of the same or greater molarity as the stannous chloride)
Gift economy Gift economy A gift economy, gift culture, or gift exchange is a mode of exchange where valuables are not traded or sold, but rather given without an explicit agreement for immediate or future rewards. This exchange contrasts with a barter economy or a market economy, where goods and services are primarily exchanged for value received. Social norms and custom govern gift exchange. Gifts are not given in an explicit exchange of goods or services for money or some other commodity. The nature of gift economies forms the subject of a foundational debate in anthropology. Anthropological research into gift economies began