Is heat, gas production, and color change can all be evidence of chemical change

Dissolving 3.05 g of an impure sample of CaCO₃ in an excess of HCl acid produced 0.636 L of CO₂ (measured at 25°C and 792 mmHg). Calculate the percent by mass of CaCO₃ in the sample. State any assumptions.

Calculate the ph of a buffer solution obtained by dissolving 13.0 g of kh2po4 (s) and 26.0 g of na2hpo4 (s) in water and then diluting to 1.00 l.

If a gas occupies 12.60 liters at a pressure of 1.50 atm, what will its pressure at a volume of 2.50 liters?

Washing soda is a hydrate of sodium carbonate. Its formula is Na2CO3. x H2O. A 2.714 g Sample of washing soda is heated until a constant mass of 1.006 g of Na2CO3 is reached. What is x?

How much heat is needed to raise the temperature of 75 g of a substance by 15 C when the specific heat is 0.92 J/g-C?

A chemical is placed in a beaker containing 20 g of soil and 500 mL of water. At equilibrium, the chemical is found in the soil ast a concentration of 100 mg. kg-1 of soil.

A solid reactant is placed into a beaker of warm water. The liquid vigorously bubbles as the soild dissolves into the solution. What will most likely happen if the temperature of the liquid is slightly reduced

How does the space between atoms change as agas goes through prase changes to become a soild? how. do they different? use words to describe

What is an endothermic reaction? O A. A reaction that produces heat O B. A reaction that uses radiation waves C. A reaction that absorbs heat O D. A reaction that contains enthalpy

How does the conservation of matter relate to balancing equations?