Chemistry Answers

10³ of hydrogen gas sparked with 20cm³ of oxygen, calculate the volumes of residual gasses after cooling

In the decomposition of phosphoric acid, H3PO4(s), pyrophosphoric acid and water form. How many moles of phosphoric acid are needed to produce 8.34mol of pyrophosphoric acid?

A hydrocarbon Y of molecular mass 46 consists of 52.2% carbon 13.0 hydrogen and rest oxygen by mass(C=12,H=1,O=16)

a)calculate th empirical formula of Y

b)Determine the molecular formula of Y

The analysis of an unknown compound shows that it is made up of 14.14% C, 2.37% and 83.48% O. What is the chemical formula of the compound if it’s molar mass is 84.93g/mol?

Write the equation for the reaction between potassium oxide and

1)water

2)hydrochloric acid

If ΔH is -29.3 J and the H_Products is 125.9 J, what is the H_Reactants? Show your work.

If H _Products is 12 J and H _Reactants is 34 J, what is the ΔH of the reaction? 

Hydrides of Silicon

We place a metal rod weighing 5.00 g with a specific heat capacity of 0.490 J/K/g in 23.5 mL of water. The specific heat capacity of water is 4.184 J/K/g and we make the approximation that its density is exactly 1.000 g/mL. The water has an initial temperature of 20.0 °C and the metal rod has an initial temperature of 81.0 °C. What is the final temperature (in oC) of the water and metal rod?

The standard enthalpies of formation, at 25.00 °C, of methane (CH4(g)), water (H2O(I), and carbon dioxide (CO2(g)) are, respectively,-74.6 kJ/mol, -285.8 kJ/mol, and-393.5 kJ/mol. Calculate the amount of heat released (in kJ) during the combustion of 17.52 L of methane under a constant pressure of 1.000 atm at 25.00 °C (N.B. combustion is the reaction with molecular oxygen to produce water and carbon dioxide.) Q