Ice floats in water due to the physical properties determined by the chemical arrangement of solid water (ice). Physically, why does ice float in water (2 points) and what is the chemical arrangement of ice that allows it to float (2 points)? 

(WCSU25) Acetylene (C2H2) gas is burned in welding and produces enough heat to melt metals and allow them to be fused together. a. Balance the chemical reaction below. C2H2(g)    +    O2(g)      

Which side effect is associated with MDMA?

(WCSU25) Provide the formal charges of the nitrogen and starred (*) oxygen in the following molecule.   N: O*:

(WCSU25) Select the intermolecular force(s) that are present in: CH3CH2OH

23. (WCSU25., 6 points) The balanced combustion reaction for methane is shown. CH4 (g)       +       2 O2 (g) 

(WCSU25) Select the intermolecular force(s) that are present in: CO2(s)

16. (WCSU25., 6 points) Draw two constitutional isomers having the formula C4H8O.  Use two different functional groups and label them by name.   Enter the number of sigma bonds in one isomer below:

21.  (WCSU25.) The ocean is said to contain one hundred trillion million dollars of gold (Au) in the form of gold(III) chloride.  For decades, chemists (and wannabes) have attempted to precipitate gold from seawater, albeit unsuccessfully.  One method would be to form an insoluble gold salt. Then, by a redox reaction, reduce the gold ions to pure gold ($$$!). a.  (6 points) In theory, sodium hydroxide could be used to precipitate gold from seawater.  Write the net ionic equation for the reaction below. Start with the complete ionic equation and identify spectators. AuCl3(aq)    +   3 NaOH (aq) ⟶  Au(OH)3 (s)     +    3 NaCl (aq)   b.  (4 points) Provide an alternative anion to hydroxide that could be used to precipitate gold in a similar reaction.  Write the formula of the insoluble product.  Explain in a few words how you selected the ion.   c. (12 points) You want to test the reaction in the lab before you head out to the ocean.  Calculate the mass (in g) of solid gold hydroxide (MW = 247.99 g/mol) that would form if 30 mL of a 0.200 M AuCl3 solution was mixed with 0.75 g of solid NaOH (MW = 40.0 g/mol). SHOW ALL WORK.   d.  (5 points) Calculate the percent yield if 0.98 g of precipitate are formed. (If you are unable to reach an answer in part c, you may use 3.0 g as the theoretical yield.)   Enter the percent yield in the box below.

The neurotransmitter systems that are involved in schizophrenia: