9) How do you know a chemical change has occurred?

a. New bonds have formed or bonds have broken.

b. The matter has had a change in state.

c. The temperature has changed.

d. All of the above

e. Only a and c are indicators of a chemical change.

Calculate the molality of a solution prepared by dissolving 25.0 g of sodium chloride (NaCl) in 625 g of water

In a competition reaction, equimolar amounts of the four alkanes shown were allowed to react with a limited amount of Cl_2 at 300 degree C. Which one of these alkanes would be depleted most from the mixture? propane pentane butane 2-methylpropane

What type of molecule is formed when a halogen combines with hydrogen

1. Calculate the concentration of hydronium ion of both buffer solutions at their starting pHs. Calculate the moles of hydronium ion present in 20.0 mL of each buffer. 2.

Which terrestrial planet is smallest

Which physical method can be used for obtaining a sample of salt from a small beaker of salt water? boiling freezing chromatography sorting

Science is a unique field of thought because it relies on to describe the world. •Observations and experim •Teachers and students •Books and writings •Scientists and statements

Hemoglobin, a protein in red blood cells, carries o2 from the lungs to the body's cells. iron (as ferrous ion, fe2+) makes up 0.33 mass % of hemoglobin. if the molar mass of hemoglobin is 6.8 Ã 104 g/mol, how many fe2 + ions are in one molecule?

What could you predict about a methane molecule that would most likely be made by using both the quantum model of the atom and John Dalton's model?

What is the molar mass of an unknown hydrocarbon whose density is measured to be 1.97 g/l at stp?