4. Data: Substance H2O(l) CO2(g) Ethane, C2H6(g) Ethene, C2H4(g) DHfq/kJ mol-1 –285.5 –393 –83.6 +52.6 (a) Write equation for the complete combustion of: (i) ethane (ii) ethene (iii) hydrogen (b) Calculate the enthalpy of combustion in each case. (c) From the results obtained in (b), calculate the enthalpy change for the reaction: C2H4(g) + H2(g) ® C2H6(g)

What overall charge must all compounds have

Astudent conducts an experiment to determine how the amount of water given to a plant affects its growth. what is the independent variable for this experiment?

For a family dinner, jose’s mom baked a loaf of bread. during the meal, his grandmother commented, “this bread is so dense! ” what do you think his grandmother meant by the word dense? you have some ideas regarding density already, but this experiment will enrich your understanding of the relationship between mass, volume and the density of objects. when making measurements in this experiment we will be using si units, the international system of units. the purpose of using si units is to have the ability to communicate and compare data results with other experiments without having to make conversions. measurement symbol si unit length m meter mass kg kilogram volume l liters density kg/l kilograms per liter any calculations that are performed during this experiment will ultimately be reported in scientific notation. recall that scientific notation is extremely important when we have data that is extremely small or large. scientists rely on a standard form of communication to quickly make hypotheses and judgements based on data. what is the density of block a? a0kg/l what is the density of block b? a1kg/l what is the density of block c? a2kg/l what is the density of block d? a3kg/l what is the density of block e? a4kg/l which block is the densest? a5