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3 years ago

Please help. I will post another sheet because I need help, thanks!

Chemistry

1 answer:

Sliva [168]3 years ago

8 0

The last one will be It's better to use the average data instead of the single trail because the average you don't have to multiply add subtract and all that nonsense but if you use the single trail you will have to do all the adding multiplying etc.

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which tool was mostly likely used in a procedure if the lab report shows that approximately 300 ml of water was used

DiKsa [7]

it is most likely a beaker, beacuse 300ml is quite a large volume. Otherwise, it would be a measuring cylinder or pippette

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3 years ago

Which should be kept away from heat sources? Check all that apply.

Maru [420]

Answer:

loose hair, flammable clothing, and all stored chemicals especially flammable liquids., should be kept away from heat.

A fire blanket is a highly flame-resistant blanket that can be used to extinguish a small fire or to wrap around a person in case of a fire and water helps put it out too.

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3 years ago

Read 2 more answers

Calculate the enthalpy of the reaction

harkovskaia [24]

Answer : The enthalpy of the reaction is, -2552 kJ/mole

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The given enthalpy of reaction is,

$4B(s)+3O_2(g)\rightarrow 2B_2O_3(s)$ $\Delta H=?$

The intermediate balanced chemical reactions are:

(1) $B_2O_3(s)+3H_2O(g)\rightarrow 3O_2(g)+B_2H_6(g)$ $\Delta H_A=+2035kJ$

(2) $2B(s)+3H_2(g)\rightarrow B_2H_6(g)$ $\Delta H_B=+36kJ$

(3) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l)$ $\Delta H_C=-285kJ$

(4) $H_2O(l)\rightarrow H_2O(g)$ $\Delta H_D=+44kJ$

Now we have to revere the reactions 1 and multiple by 2, revere the reactions 3, 4 and multiple by 2 and multiply the reaction 2 by 2 and then adding all the equations, we get :

(when we are reversing the reaction then the sign of the enthalpy change will be change.)

The expression for enthalpy of the reaction will be,

$\Delta H=-2\times \Delta H_A+2\times \Delta H_B-6\times \Delta H_C-6\times \Delta H_D$

$\Delta H=-2(+2035kJ)+2(+36kJ)-6(-285kJ)-6(+44)$

$\Delta H=-2552kJ$

Therefore, the enthalpy of the reaction is, -2552 kJ/mole

4 0

3 years ago

An acid

tekilochka [14]

The answer is A. Has a low pH in solution.

5 0

3 years ago

Which of the following represents a physical change?

vivado [14]

A. phase changing. Physical change is any change in matter that involves the substance going from one physical state to another, and phase change is most commonly used to describe transitions between solid, liquid and gaseous states of matter.

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3 years ago