The reaction between magnesium and hydrochloric acid is exothermic, so it releases heat. This could be a problem for Gemma's investigation because temperature also affects reaction rate. The rise in temperature could, therefore, influence the outcome in addition to the independent variable, concentration.Describe one way that Gemma could deal with this problem to improve the validity of her experiment.

A student investigated how temperature affects the rate of reaction between magnesium carbonate and dilute hydrochloric acid. This is the method used.Heat hydrochloric acid to 30 oC in a conical flask.Add magnesium carbonate powder to the conical flask.Measure the loss in mass of the flask and contents every 20 seconds for 140 seconds.Repeat steps 1-3 with hydrochloric acid heated to 50 oCExplain why the contents of the conical flask lose mass.

Magnesium metal reacts with hydrochloric acid according to Reaction 1.Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)Reaction 1During an experiment to measure the molar enthalpy ΔH° of Reaction 1, a student placed 100. mL of dilute HCl(aq) into a coffee cup calorimeter, as shown in Figure 1.Figure 1  Coffee cup calorimeterAfter monitoring the solution temperature for 1 min, 0.486 g of Mg(s) was then added to the solution inside the calorimeter and stirred while continuing to monitor the temperature until the Mg(s) was completely consumed.  The results of the experiment are shown on the graph in Figure 2.Figure 2  Graph of temperature versus time during the reaction of magnesium with hydrochloric acidAccording to the first law of thermodynamics, the heat produced (or consumed) by a reaction qrxn must be equal to the heat transferred to (or taken from) the surroundings (ie, the solution and the calorimeter), as expressed by Equation 1.−qrxn = qsurroundings = qsolution + qcalorimeterEquation 1 Question 41Based on the results of the calorimetry experiment described in the passage, the magnitude of the molar enthalpy ΔH° for Reaction 1 (in kJ/mol Mg) is closest to which of the following?  (Note: Assume that the HCl(aq) has a density of 1.0 g/mL and a specific heat capacity of 4.0 J/(g∙°C), and that qcalorimeter ≈ 0.)A.8.84B.18.2C.442D.844

Following are the observations of a student while working in the laboratory. Explaineach of his/ her observations with reference to chemical kinetics.a. Magnesium reacts very slowly with cold water, but extremely vigorously withsteam

Magnesium metal reacts with hydrochloric acid. At the end of the reaction there is a small amount of magnesium left at the bottom of the flask. Which of the reactants was the limiting reactant?

At 25 °C, 200 cm3 of 1.0 moldm−3 nitric acid is added to 5.0 g of magnesium powder. If the experiment is repeated using the same mass of magnesium powder, which conditions will result in the same initial reaction rate?