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Hint
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Answer
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what is △H measured in usually
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kJ/mol
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does the bond energy ever change
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yes, it changes slightly when it's bond is in a different compound
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what 5 things would you increase to increase the rate of reaction, in ascending alphabetical order
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catalyst, concentration of a liquid, pressure of gas, surface area of solid, temperature.
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what happens when ammonium chloride is thermally decomposed
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produces hydrogen chloride gas and nitrogen
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what is calorimetry
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measures amount of energy transferred in a chemical reaction
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what is the molar enthalpy change
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enthalpy change per mole of a substance
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state the equation for moles
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moles = mass/Mr
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what does the position of equilibrium depend on
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pressure and temperature of reactants
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what can concentration be measured in
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describe and explain how to increase the rate of reaction without increasing the reactants abundance
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Increase the temperature of the substance, this gives the particles more kinetic energy, allowing them to move faster which means they will collide with each other more frequently. Also a higher proportion of the collisions will be successful as the collision energy will be greater than or equal to the activation energy, this means the reaction can take place more often. All of this increases the rate of reaction very well which is why increasing the temperature is one of if not the most efficient way to increase the rate of reaction.
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what does ventilated mean
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an area that's air is well circulated
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in an exothermic reaction, is △H negative or positive
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negative
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what will happen if you carry out the calcium carbonate and hydrochloric acid experiment but with bigger marble chips with a total mass of the same before, like you have joined the smaller marble chips together
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these bigger marble chips have a smaller surface area, so reaction will be slower. The same carbon dioxide is produced as it has the same mass, but it takes longer for it to reach the maximum carbon dioxide produced. So it takes longer for the line to plateau or become flat. It is less steep to begin, showing it's slower than before.
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999999999999999999
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how do we vary the concentration of sodium thiosulfate in the reaction between sodium thiosulfate and hydrochloric acid
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the volumes of water and sodium thiosulfate are varied. but the total volume of the 2 need to be kept the same otherwise we are looking at the effect of volume on the rate of reaction, but we want to look at the effect of concentration. The results are recorded and placed on a table and graph.
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do all bonds have a bond energy
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yes
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does breaking bonds need energy
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yes
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what can't a catalyst affect in a reversible reaction
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position of equilibrium
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in an endothermic reaction, is △H negative or positive
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positive
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why do the reactants bonds need to be broken in a chemical reaction
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to make new bonds which forms the products
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what is the activation energy
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minimum amount of energy a chemical reaction needs in order to take place
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what's a bond energy
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strength of a chemical bond
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does forming bonds need energy
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no
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state the word equation between calcium carbonate and Hydrochloric acid in alphabetical order
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calcium carbonate + hydrochloric acid ─> calcium chloride + water + carbon dioxide
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99999999999999999999
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describe how to carry out experiment between sodium thiosulfate and hydrochloric acid
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1: draw a large cross onto a piece of paper 2: place a conical flask onto the cross 3: pour sodium thiosulfate and hydrochloric acid into the beaker 4: observe the reaction directly above the flask 5: record the time taken for the cross to vanish 6: the cross vanishes because the yellow sulfur precipitate is formed |
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is breaking bonds endothermic or exothermic
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endothermic
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what does the energy released by the forward direction equal
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energy absorbed by the backward direction
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what can the units of rate of reaction be
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how do we see what catalysts are the best at decomposing hydrogen peroxide
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experiment with different catalysts
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what happens when hydrated copper (ii) sulfate is thermally decomposed
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forms water and anhydrous copper (ii) sulfate in an exothermic reaction
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is the dehydration of copper (ii) sulfate exothermic
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no
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what is conservation of energy
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energy isn't created or destroyed in a chemical reaction
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what is the unit cm³ the same as
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grams
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what is a reaction profile a.k.a
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energy level or energy profile
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what is the difference in energy known as in a reaction profile
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△H
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state the equations for the rate of reaction
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rate of reaction = mass of product formed / time
rate of reaction = mass of reactant used / time |
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state the word equation in the thermal decomposition of ammonium chloride
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ammonium chloride ⇌ nitrogen + hydrogen chloride
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describe and explain how to increase the rate of reaction with a gas without increasing temperature
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Increase the pressure of a gas, this means the same particles are present in a smaller volume which means there is less room for the gases to not react, so there are more particles per unit of volume as there is less volume for them to travel in. This makes more room for collisions so they will be more frequent which increases the rate of reaction.
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when is the reaction exothermic
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when the total energy released by making new bonds is higher than the total energy needed to break bonds
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9999999999999999999
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what is the enthalpy change
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change in heat during a reaction at constant pressure
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state the chemical equation between ethanol and oxygen
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C₂H₅OH + 3O₂ ─> 2CO₂ + 3H₂O
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what poisonous gas is produced during the reaction between sodium thiosulfate and hydrochloric acid and how do we prevent getting harmed
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sulfur dioxide is produced which dissolves in water to give an acidic solutionof sulfurous acid. The reaction is carried out in a well ventilated room so we don't get harmed.
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can reactions have more gas molecules on one side
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yes
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describe how to carry out the experiment between Hydrochloric acid and calcium carbonate
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marble chips react with hydrochloric acid to give calcium chloride solution, water and carbon dioxide gas. 1: put a beaker onto a mass balance 2: place hydrochloric acid in the beaker 3: place marble chips in the beaker containing HCl 4: put cotton wool instead of a bung on top of the beaker to stop acid spraying out and escaping, ruining the results and to allow carbon dioxide to escape so we can measure how much was lost 5: The change in mass of beaker is measured and put on a graph 6: the change in mass is the carbon dioxide escaping 7: This is because as marble chips react with the acid, carbon dioxide is released 8: the mass of carbon dioxide lost is measured and recorded at regular intervals |
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state the equation for △H
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△H = Q/mol
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what happens when hydrogen chloride and nitrogen are cooled
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produces ammonium chloride
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state the △H, increased temperature change, energy of products and reactants and the type of reaction of
CH₄ + H₂O ⇌ CO + 3H₂ |
it's an endothermic reaction because the forward direction is endothermic, we know this because our H₂O and CH₄ molecules are no where to be seen, so they must've been broken and bond breaking is endothermic so our reaction is endothermic. An endothermic reaction has a positive △H because reactants have less energy than products because reactants lose energy to the products meaning the △H is positive. If temperature is increased the position of equilibrium shifts to the right. This is because an increase in temperature means the surroundings get hotter, an endothermic reaction absorbs heat, this will counteract the warmth. balancing it out, restoring equilibrium. So we want to shift the position of equilibrium to the endothermic direction. This is the right, so position of equilibrium shifts to the right. So more product is made.
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99999999999999999
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how can a reaction be endothermic if the total energy released equals the total absorbed
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total energy needed to break all bonds is different for every compound
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what colour is ammonium chloride powder
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white
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what type of calcium carbonate should you use to get the slowest rate of reaction
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one big chunk of calcium carbonate
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9999999999999999999
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how do you calculate △H using bond energies
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Energy needed to break bonds - Energy released when forming bonds
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