What element has the atomic number 11

What does it mean to say water is 11% hydrogen by mass

Consider the reaction 2Al (OH) 3 (s) →Al2O3 (s) + 3H2O (l) with enthalpy of reaction ΔHrxn∘=21.0kJ/mol What is the enthalpy of formation of Al2O3 (s) ?

How do you find a theoretical mass? Is there a difference between theoretical mass and theoretical yield?

By making several measurements with the same balance, a chemist obtained values of 5.224 g, 5.235 g, and 5.259 g for the mass of a sample. Without knowing the actual mass of the sample, we can tell that these measurements have.

In the following reaction, oxygen is the excess reactant. SiCl4 + O2 → SiO2 + Cl2 The table shows an experimental record for the above reaction.

The graph below shows how solubility changes with temperature. What is the solubility of Na2HAsO4 at 60°C? 20 g/100 mL of water 46 g/100 mL of water 65 g/100 mL of water 70 g/100 mL of water

Which statement regarding water is true? Energy must be given off in order to break down the crystal lattice of ice to a liquid. Hydrogen bonds are stronger than covalent bonds. Liquid water is less dense than solid water.

Which of the following elements has the fewest valence electrons?. a. beryllium. b. boron. c. carbon. d. lithium

How many molecules are in 4.50 moles of H2O? A. 450 molecules B. 6.02 x 1023 molecules C. 2.71 x 1024 molecules D. 3.00 molecules

A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. How much calcium is contained in 45.0 g of calcium fluoride