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Yuki888 [10]
3 years ago
14

Using the following thermochemical data, what is the change in enthalpy for the following reaction?

Chemistry
1 answer:
Mice21 [21]3 years ago
5 0
In calculating the change in enthalpy in a certain reaction, it is important to remember that it is the sum of the enthapy of formation for the substances involved in the reaction. 

<span>CaO(s)+2HCl(aq)→CaCl2(aq)+H2O(l)                          ΔH= –186kJ 
</span>Ca(OH)2(aq) →  CaO(s)+H2O(l)<span>                                     ΔH= 65.1 kJ
</span>Ca(OH)2(aq) + 2HCl(aq) → CaCl2(aq) + 2H2O(l)       ΔH= -120.9 kJ
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3 years ago
A student balanced the chemical equation Mg + O2 →MgO by writing Mg + O2 → MgO2. Was the equation balanced correctly? Explain yo
Amanda [17]

Explanation:

Charges on both magnesium and oxygen is 2. Though opposite in sign, they have equal charges so, both of them will be cancelled by each other.

As a result, formula of magnesium oxide is MgO and not MgO_{2}.

The student write the equation as Mg + O_2 \rightarrow MgO_2, it is not correct.

Therefore, given equation will be balanced as follows.

          2Mg + O_{2} \rightarrow 2MgO

Since, number of atoms on both reactant and product side are equal. Hence, this equation is completely balanced.

7 0
3 years ago
Which statement explains the relationship between the amount of energy it takes to break a bond and the amount of energy release
ad-work [718]

<em>The statement that gives the relationship between energy needed in breaking a bond and the one that is released after breakin</em>g is

The amount of energy it takes to break a bond is always less than the amount of energy released when the bond is formed.

  • Bond energy can be regarded as amount of energy that is required in  breaking a particular bond.

  • For a bond to be broken Energy will be  added and when a bond is broken there will be release of energy

  • Bond breaking can be regarded as endothermic process, it is regarded as endothermic  because there is a lot of energy required to be absorbed.

  • Where ever a bond is broken, there must be formation of another bond

  • Bond forming on the other hand can be regarded as exothermic process, since there is a release of  releases energy.

Therefore, more energy is required in breaking of bond compare to energy released after breaking of bond.

Learn more at : brainly.com/question/10777799?referrer=searchResults

6 0
3 years ago
A 2.50 g sample of solid sodium hydroxide is added to 55.0 mL of 25 °C water in a foam cup (insulated from the environment) and
zlopas [31]

Answer:

37.1°C.

Explanation:

  • Firstly, we need to calculate the amount of heat (Q) released through this reaction:

<em>∵ ΔHsoln = Q/n</em>

no. of moles (n) of NaOH = mass/molar mass = (2.5 g)/(40 g/mol) = 0.0625 mol.

<em>The negative sign of ΔHsoln indicates that the reaction is exothermic.</em>

∴ Q = (n)(ΔHsoln) = (0.0625 mol)(44.51 kJ/mol) = 2.78 kJ.

  • We can use the relation:

Q = m.c.ΔT,

where, Q is the amount of heat released to water (Q = 2781.87 J).

m is the mass of water (m = 55.0 g, suppose density of water = 1.0 g/mL).

c is the specific heat capacity of water (c = 4.18 J/g.°C).

ΔT is the difference in T (ΔT = final temperature - initial temperature = final temperature - 25°C).

∴ (2781.87 J) = (55.0 g)(4.18 J/g.°C)(final temperature - 25°C)

∴ (final temperature - 25°C) = (2781.87 J)/(55.0 g)(4.18 J/g.°C) = 12.1.

<em>∴ final temperature = 25°C + 12.1 = 37.1°C.</em>

6 0
3 years ago
What kind of glacier has pieces that breaks off as icebergs
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There is no specific name for a glacier that break off as an iceberg. However, the part of the glacier in which this happens is called the "zone of wastage". Chunks break off in a process called "calving".
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