To extract gold from its ore, the ore is treated with sodium cyanide solution in the presence of oxygen and water. 4 Au(s) + 8 NaCN(aq) + O2(g) + 2 H2O(l) 4 NaAu(CN)2(aq) + 4 NaOH(aq)
(a) Determine the mass of gold that can be extracted if 21.7 g sodium cyanide is used.

(b) If the mass of the ore from which the gold was extracted is 161.5 g, what percentage of the ore is gold?

Which statement is true about the part of the electromagnetic spectrum that human eyes can detect? it contains only the colors of the rainbow and television waves. o it is divided into seven ranges of wavelengths. it contains ultraviolet, visible, and infrared light. it is divided into nine ranges of wavelengths.

In a laboratory experiment, a fermenting aqueous solution of glucose and yeast produces carbon dioxide gas and ethanol. the solution was heated by burning natural gas in a bunsen burner to distill the ethanol that formed in the flask. during the distillation, the ethanol evaporated and then condensed in the receiving flask. the flame of the burner was kept too close to the bottom of the flask and some of the glucose decomposed into a black carbon deposit on the inside of the flask. during this experiment the following changes occurred. which of these changes involved a physical change and not a chemical change? check all that apply. 1-condensation of ethanol 2-evaporation of ethanol 3- formation of carbon dioxide gas from glucose burning of natural gas 4-formation of ethanol from glucose by yeast 5-formation of a carbon deposit inside the flask

You are making a solution of calcium chloride dissolved in water. you add solid, stir, and it dissolves. you add just a spatula tip full, stir, and the solid does not dissolve. how could you describe the solutions before and after adding the spatula tip amount