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Schach [20]
3 years ago
15

A student determines the density of an element to be 2.73 g/cm 3 . If the accepted value is 2.70 grams per cm 3 , what is the st

udent's percent error? Identify the element. What is the boiling of this element in Celsius degree
Chemistry
1 answer:
Brums [2.3K]3 years ago
8 0

Answer:

Explanation:

percentage error = error  x 100 / correct value

= (2.73 - 2.70) x100 / 2.70

= 1.11 %

The element is Aluminium whose density is 2.702 grams / cc

Boiling point of Aluminium = 2519⁰C .

You might be interested in
A scientist measures the standard enthalpy change for the following reaction to be 67.9 kJ:
bekas [8.4K]

Answer: The standard enthalpy of formation  of H_2O(g) is  -252.1 kJ/mol.

Explanation:

The balanced chemical reaction is,

Fe_2O_3(s)+3H_2(g)\rightarrow 2Fe(s)+3H_2O(g)

The expression for enthalpy change is,

\Delta H=[n\times H_f_{products}]-[n\times H_f_{reactantss}]

Putting the values we get :

\Delta H=[2\times H_f{Fe}+3\times H_f{H_2O}]-[1\times H_f{Fe_2O_3}+3\times H_f{H_2}]

67.9kJ=[(2\times 0)+(3\times H_f{H_2O})]-[(1\times -824.2kJ/mol)+3\times 0kJ/mol)]

H_f{H_2O}=-252.1kJ/mol

Thus standard enthalpy of formation  of H_2O(g) is  -252.1 kJ/mol.

3 0
2 years ago
The half-life of cesium-137 is 30 years. Suppose we have a 200-mg sample. (a) Find the mass that remains after t years.
scZoUnD [109]

Given:

Half life(t^ 1/2) :30 years

A0( initial mass of the substance): 200 mg.

Now we know that

A= A0/ [2 ^ (t/√t)]

Where A is the mass that remains after t years.

A0 is the initial mass

t is the time

t^1/2 is the half life

Substituting the given values in the above equation we get

A= [200/ 2^(t/30) ] mg


Thus the mass remaining after t years is [200/ 2^(t/30) ] mg

5 0
3 years ago
What are some things we breathe in
Gre4nikov [31]

Answer:

The majority of the air we breathe is made up of nitrogen and oxygen, though you'll also find argon, carbon dioxide and other gases in trace amounts.

Explanation:

7 0
3 years ago
Number of
Sever21 [200]

Answer:1:En química, el número másico o número de masa es la suma del número de protones y el número de neutrones del núcleo de un átomo. Se simboliza con la letra A (el uso de esta letra proviene de alemán Atomgewicht, que quiere decir peso atómico, aunque sean conceptos distintos que no deben confundirse).

2:

4 0
3 years ago
A 7.12 L cylinder contains 1.21 mol of gas A and 4.94 mol of gas B, at a temperature of 28.1 °C. Calculate the partial pressure
GenaCL600 [577]

Answer:

P_A=4.20atm\\\\P_B=17.1atm

Explanation:

Hello!

In this case, since the equation for the ideal gas is:

PV=nRT

For each gas, given the total volume, temperature (28.1+273.15=301.25K) and moles, we can easily compute the partial pressure as shown below:

P_A=\frac{n_ART}{V} =\frac{1.21mol*0.082\frac{atm*L}{mol*K}*301.25K}{7.12L} \\\\P_A=4.20atm\\\\P_B=\frac{n_BRT}{V} =\frac{4.94mol*0.082\frac{atm*L}{mol*K}*301.25K}{7.12L} \\\\P_B=17.1atm

Best regards!

8 0
2 years ago
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