Chemistry, 22.10.2020 20:01 bcifuentes

calcium oxide has been proposed as a substance. calculate the minimum mass of CaO that would be required to cause this temperature change

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Answer from: hnsanders00

The question is incomplete. Here is the complete question.

Calcium oxide, $CaO_{(s)}$ , has been proposed as a substance that can be used to heat water quickly for portable heating packs or for cooking. When placed in water, $CaO_{(s)}$ reacts as shown by hte equation below:

$CaO_{(s)}+H_{2}O_{(l)}$ ⇄ $Ca(OH)_{2}_{(s)}$

a) A student wants to design a heating pad that could heat a 150.0 g sample of water from 25.0°C to 60.0°C.

(i) Calculate the amount of heat, in joules, that the water must absorb for its temperature to change by this amount. (Assume that specific heat capacity of water is 4.18J/(g.°C).)

(ii) Calculate the minimum mass of $CaO_{(s)}$ that the student would need to use in order to cause this temperature change.

(i) Q = 21,945J

(ii) m = 467.87g

Explanation: Energy necessary for the water to absorb to heat up is calculated by:

$Q=mc\Delta T$

Q is heat

c is specific heat capacity, in this case in J/g.°C

$\Delta T$ is change in temperature

(i) Calculating amount of heat:

Q=150*4.18*(60-25)

Q = 21945J

The water needs 21,945 joules to increase by that amount of temperature.

(ii) According to the chemical equation:

$CaO_{(s)}+H_{2}O_{(l)}$ ⇄ $Ca(OH)_{2}_{(s)}$

it is needed 1 mol of each reagent to produce 1 mol of product.

Molar mass of water is 18g/mol. For 150g, there are:

n = $\frac{150}{18}$

n = 8.34 mols

Molar mass of CaO is 56.1g/mol. For 8.34 mols:

m = 8.34*56.1

m = 467.87g

For calcium oxide to increase temperature in 35°C, the minimum necessary is 467.87 grams.

Answer from: Quest

For cyclohexane compounds drawn in a chair conformation: -axial bonds are vertical -equatorial bonds are parallel to two bonds within the ring. thus, as i assume the chair conformation is drawn: -the x group is in an axial position, as are the five other vertical bonds. -three axial bonds are on the top face of the ring -the other three axial bonds are on the bottom face the position of the second substituent on each ring carbon is equatorial. gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other. drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1. click this link and watch some academic videos that may you more understand the topic

Answer from: Quest

the answer is 1260

you spend 7 hours in school for 1 school day with 5 school days in 1 school week with 36 school weeks in a school year.

7*5*36= 1260 it's all about multiplying

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