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34kurt
3 years ago
14

True or false

Chemistry
1 answer:
8090 [49]3 years ago
5 0
1) false, they can’t
2) false, algae produces oxygen and are a source of food for other organisms
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A 237g sample of molybdnum metal is heated to 100.1 0C and then dropped into an insulated cup containing 244 g of water at 10.0
miv72 [106K]

Answer:

The specific heat of molybdenum is 0.254 joules per gram-Celsius.

Explanation:

We consider the system formed by the molybdenum metal and water as our system, a control mass inside an insulated cup, that is, a container that avoids any energy and mass interactions between system and surroundings.

From statement we notice that metal is cooled down whereas water is heated. According to the First Law of Thermodynamics, we know that:

Q_{metal} - Q_{water} = 0

Q_{metal} = Q_{water}

Where:

Q_{water} - Heat received by water, measured in joules.

Q_{metal} - Heat released by metal, measured in joules.

Now we expand this identity by definition of sensible heat:

m_{metal}\cdot c_{metal}\cdot (T_{m,o}-T) = m_{water}\cdot c_{water}\cdot (T-T_{w,o})

The specific heat of the metal is cleared within equation above:

c_{metal} = \frac{m_{water}\cdot c_{water}\cdot (T-T_{w,o})}{m_{metal}\cdot (T_{m,o}-T)}

If we know that m_{water} = 0.237\,kg, m_{metal} = 0.244\,kg, c_{water} = 4186\,\frac{J}{kg\cdot ^{\circ}C}, T_{w,o} = 10\,^{\circ}C, T_{m,o} = 100.10\,^{\circ}C and T = 15.30\,^{\circ}C, the specific heat of molybdenum is:

c_{metal} = \frac{(0.237\,kg)\cdot \left(4186\,\frac{J}{kg\cdot ^{\circ}C} \right)\cdot (15.30\,^{\circ}C-10\,^{\circ}C)}{(0.244\,kg)\cdot (100.10\,^{\circ}C-15.30\,^{\circ}C)}

c_{metal} = 254.119\,\frac{J}{kg\cdot ^{\circ}C}

The specific heat of molybdenum is 0.254 joules per gram-Celsius.

5 0
3 years ago
Can somebody help me with this also plz
just olya [345]

ANSWER:

4 a) Specific elements have more than one oxidation state, demonstrating variable valency.

For example, the following transition metals demonstrate varied valence states: Fe^{2+}, Fe^{3+}, Cr^{2+}, Cr^{3+}, etc.

Normal metals such as Pb^{2+} and Pb^{4+} also show variable valencies. Certain non-metals are also found to show more than one valence state Pb^{3+} and Pb^{5+}.

4 b) Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons.

For example, Carbon-14 is a naturally occurring radioactive isotope of carbon, having six protons and eight neutrons in the nucleus. However, C-14 does not last forever and there will come a time when it loses its extra neutrons and becomes Carbon-12.

5 a) 2Fe + 3Cl_2 → 2FeCl_3    

5 b) 3Pb + 8HNO_3 → 3Pb (NO_3)_2 + 4H_2O + 2NO_2

5 c) Zn + H_2SO_4 → ZnSO_4 + H_2   (already balanced so don't need to change)

5 d) 2H_2 + O_2 → 2H_2O

5 e) 2Mg + 2HCl → 2MgCl + H_2

EXPLANATION (IF NEEDED):

1. Write out how many atoms of each element is on the left (reactant side) and right (product side) of the arrow.

2. Start multiplying each side accordingly to try to get atoms of the elements on both sides equal.

EXAMPLE OF BALANCING:

8 0
2 years ago
Why does burned toast taste so bad? Is it a chemical or physical change?
german

Because things that are burnt have been changed into something else like moldy bread thats cooked.

It is chemical change because you cannot unburn something.

4 0
3 years ago
Read 2 more answers
At 150°C the decomposition of acetaldehyde CH3CHO to methane is a first order reaction. If the
Crank

The decomposition time : 7.69 min ≈ 7.7 min

<h3>Further explanation</h3>

Given

rate constant : 0.029/min

a concentration of  0.050 mol L  to a concentration of 0.040 mol L

Required

the decomposition time

Solution

The reaction rate (v) shows the change in the concentration of the substance (changes in addition to concentrations for reaction products or changes in concentration reduction for reactants) per unit time

For first-order reaction :

[A]=[Ao]e^(-kt)

or

ln[A]=-kt+ln(A0)

Input the value :

ln(0.040)=-(0.029)t+ln(0.050)

-3.219 = -0.029t -2.996

-0.223 =-0.029t

t=7.69 minutes

4 0
3 years ago
What is the same for all of the drilling sites we examined?
yarga [219]

Answer:

the same is what is this question like what did u exame

4 0
3 years ago
Read 2 more answers
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