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sergij07 [2.7K]
3 years ago
8

Blood samples for research or medical tests sometimes have heparin added. Why is this done? ​

Chemistry
1 answer:
alina1380 [7]3 years ago
8 0
It is essential for accurate results that the correct volume of blood is sampled to achieve a correct concentration (and dilution, if liquid heparin is used), and that blood and anticoagulant are well mixed immediately after sampling.
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Determine the amount of heat(in Joules) needed to boil 5.25 grams of ice. (Assume standard conditions - the ice exists at zero d
Yuki888 [10]
Following are important constant that used in present calculations
Heat of fusion of H2O = 334 J/g 
<span>Heat of vaporization of H2O = 2257 J/g </span>
<span>Heat capacity of H2O = 4.18 J/gK 
</span>
Now, energy required for melting of ICE = <span>  334 X 5.25 = 1753.5 J .......(1)
Energy required for raising </span><span>the temperature water from 0 oC to 100 oC =  4.18 X 5.25 X 100 = 2195.18 J .............. (2)
</span>Lastly, energy required for boiling water = <span>  2257X 5.25 = 11849.25 J ......(3)
</span><span>
Thus, total heat energy required for entire process = (1) + (2)  + (3)
                                                                        = 1753.5 + 2195.18 + 11849.25
                                                                        = </span><span>15797.93 J 
</span><span>                                                                        = 15.8 kJ
</span><span>Thus, 15797.93 J of energy is needed to boil 5.25 grams of ice.</span>
7 0
3 years ago
PLEASE PLEASE HELP ME!! I WILL BRAINLIST YOU!! A 28.0 g sample of N2 is in a rigid 4.50 L container at 32 °C. Calculate the pres
chubhunter [2.5K]

Answer:

P=4184.36 torr

Explanation:

For this problem we can use the idea gas law,

PV=nRT

where P is pressure, V is volume, n is moles of substance, R is the constant, and T is temperature, We will need to manipulate it and a couple values so that we can get our answer in torr. To do this, let's rearrange the equation to solve for P.

P=\frac{nRT}{V}

Next, let's convert T (32) to kelvin. To do this, add 273 to the value.

32+273=305

Next, let's convert 28g of N2 to moles of N2. To do this, divide 28 by the molar mass of N2 (28.02)

\frac{28.0}{28.01} \\=.99 moles of N2

Next, we need to find out what value of R we need to use. Because you want your answer in torr, we will need to use the value of

R=62.36\frac{torr}{mol*K}

Now that we have all of our values, let's plug them into the equation (I'll be excluding units for simplicity but they cancel out to leave units of torr in the answer)

P=\frac{(.99)(62.36)(305)}{4.50}\\P=4184.36

P=4184.36 torr

<em>Very briefly</em>, I don't know what your periodic table looks like, but mine has nitrogen's molar mass as 14.01. If you have a different mass of nitrogen, this pretty drastically impacts the value. For example, if your nitrogen's molar mass was rounded to 14.0 (making N2 28g) then it would be one mole instead of .99 moles, raising the answer to 4228.70 torr. If you have any different values just plug them in in their proper spots. A similar concept applies to the Kelvin conversion.

6 0
3 years ago
Examine the equation.
Alisiya [41]

Explanation:

The reaction expression is given as;

                 2H₂_{g}   +  O₂_{g}   →   2H₂O_{l}

From the balance reaction expression:

 2 mole of hydrogen gas combines with 1 mole of oxygen gas on the reactant side;

This produces 2 mole of water on the product side of the expression.

The product is in liquid form.

 This reaction is a synthesis reaction because a single product is formed from two reactants.

5 0
3 years ago
What variable represents specific heat in the equation Q = mCAT?
Brut [27]

Answer:

the variable A represented specific heat capacity

3 0
3 years ago
Pls give me the right answer
Alchen [17]
The answer to the question is D
5 0
2 years ago
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