# What is the mass of 279.54 L of C_6H_12O_6 at STP?

${C}_{6} {H}_{12} {O}_{6}$ is undoubtedly a solid. Are you sure you have the question right?
${C}_{6} {H}_{12} {O}_{6}$ is the formula for glucose, and a lot of other sugars. Glucose (and the isomeric sugars) are solids at room temperature.