Now im Not going to lie this is a chem assignment but me and my friend are having a debate over some of the following qs so can anyone help us out thats good at chemistry?
1) Which of the following is endothermic?
a) Burning magnesium metal
b) Condensation of water
c) Melting candle wax
d) Adding concentrated acid to water.
2) Which of the following statements is incorrect?
a) AN exothermic reaction releases heat and has a negative (H)
b) In an exothermic reaction the temperature of the surroundings would decrease
c) In an exothermic reaction the products have a lower empalthy (heat content) than the reactants
d) An example of an exothermic reaction is the combustion of methane.
7) The neutralization reaction between hydrochloric acid and sodium hydroxide may be represented as:
HCl(aq) NaOH(aq) -> NaCl(aq) H2O(l) 57.2KJ
In this reaction, you would expect the temperature of the resulting solution to...
a) increase, due to the reaction being endothermic
b) increase, due to the reaction being exothermic
c) decrease, due to the reaction being endothermic
d) decrease, due to the reaction being exothermic
e) There is insufficient information to predict a change to the temperature of the solution.
8) Study the following two equations:
1. H2(g) 1/2O2(g) => H2O(g) (delta H) = -242KJ
2. H2(g) 1/2O2(g) => H2O(l) (delta H) = -285KJ
The best explanation for the difference in the values of (delta H) for these two reactions is...
a) More heat is given off in equation 1 because the water is in gaseous form
b) Water vapour has greater enthalpy than liquid water so reaction 2 releases more heat energy to the surroundings
c) Water in the liquid phase has more stored energy then water vapour so reaction 2 releases less heat energy to its surroundings
d) Water in the liquid phase stores less energy than water vapour and so releases less heat energy to its surroundings.
17) which one of the following would NOT cause an increase in the RATE of a chemical reaction?
a) Addition of a catalyst
b) Increasing the concentration of the reactants
c) Decreasing the temperature of the reacting species
d) Increasing the pressure of gases involved in a reaction
I dont need you to re-write the qs or the answer, just say the qs number and the letter answer, i'd also appreciate if the answers weren't guesses and you had some history in chemistry. Thankyou for your help!
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