1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
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.
You might be interested in
The chemical mixture that composes our atmosphere is called ________.
Virty [35]
Answer: Air

Hope this helps

3 0
3 years ago
How many dm³ of hydrogen,measured at s.t.p.,would be needed to reduce 47.7g of copper(II) oxide to copper?
GaryK [48]

Answer:

Option D. 13.44

Explanation:

We'll begin by calculating the number of mole in 47.7g of copper(II) oxide, CuO.

This can be obtained as follow:

Mass of CuO = 47.7 g

Molar mass of CuO = 63.5 + 16 = 79.5 g/mol

Mole of CuO =.?

Mole = mass /Molar mass

Mole of CuO = 47.7/79.5

Mole of CuO = 0.6 mole

Next, we shall write the balanced equation for the reaction. This is given below:

CuO + H2 —> Cu + H2O

From the balanced equation above,

1 mole of CuO reacted with 1 mole of H2 to produce 1 mole of Cu and 1 mole of H2O.

Next, we shall determine the number of mole of H2 needed to react completely with 0.6 mole of CuO.

This can be obtained as follow:

From the balanced equation above,

1 mole of CuO reacted with 1 mole of H2.

Therefore, 0.6 mole of CuO will also react with 0.6 mole of H2.

Finally, we shall determine the volume occupied by 0.6 mole of H2 at STP.

This can be obtained as follow:

1 mole of H2 occupied 22.4 dm³ at STP.

Therefore, 0.6 mole of H2 will occupy = 0.6 × 22.4 = 13.44 dm³.

Therefore, 13.44 dm³ of H2 is needed for the reaction.

4 0
3 years ago
How do you work out question 1a?
Sliva [168]

Answer:

-125 kJ

Explanation:

You calculate the energy required to break all the bonds in the reactants. Then you subtract the energy to break all the bonds in the products.

                     H₂C=CH₂   +    H₂ ⟶    H₃C-CH₃

Bonds:       4C-H + 1C=C     1H-H     6C-H + 1C-C

D/kJ·mol⁻¹:  413       612        436       413      347

The formula relating ΔHrxn and bond dissociation energies (D) is

ΔHrxn = Σ(Dreactants) – Σ(Dproducts)

(Note: This is an exception to the rule. All other thermochemical reactions are “products – reactants”. With bond energies, it’s “reactants – products”. The reason comes from the way we define bond energies.)

<em>For the reactant</em>s:

Σ(Dreactants) = 4 × 413 + 1 × 612 + 1 × 436 = 2700 kJ

<em>For the products:</em>

Σ(Dproducts) = 6 × 413 + 1 × 347 = 2825 kJ

<em>For the system</em> :

ΔHrxn = 2700 - 2825 = -125 kJ

4 0
3 years ago
A student with an unknown code of Q3A conducts a qualitative analysis of her unknown. Her results indicated the formation of a y
insens350 [35]

Answer:

Grey precipitate implies the presence of silver ions

Yellow precipitate implies the presence of lead II ions

Explanation:

Qualitative analysis provides us a quick method of identifying ions present in a sample by chemical reactions involving simple reagents. Precipitates having a unique colour is formed. The identity of ions in the sample is deduced from the colour of precipitate obtained when particular reagents are added.

In the question, a precipitate containing silver ions upon standing turn into grey colour. Similarly, lead II ions give a yellow precipitate.

6 0
3 years ago
What do greenhouse gases (CO2) do to the atmosphere?
Alborosie

Answer:

they causes climate change by trapping heat and also they contribute to respiratory diseases from smog and air pollution

4 0
3 years ago
Read 2 more answers
Other questions:
  • What is variable????​
    7·2 answers
  • PLZ HELP WILL MARK BRAINLIEST I NEED INSTANT HELP THIS IS A MAJOR GRADE I THINK I KNOW THE ANSWER BUT NOT SURE IF IT'S RIGHT. PL
    5·1 answer
  • Which of the following would double the pressure on a contained gas at constant temperature?
    6·1 answer
  • If I start with 5 grams of c3h8 what is my theoretical yield of water
    9·1 answer
  • Which of the following is a pure substance?
    5·1 answer
  • A pharmacist has a 12% solution of boric acid and a 20% solution of boric acid. How much of each must he use to make 80 grams of
    8·1 answer
  • Which statements best describe plantesimals
    15·1 answer
  • Strong acids are assumed 100% dissociated in water. True As a solution becomes more basic, the pOH of the solution increases. Fa
    8·1 answer
  • What is a meteorite?
    8·1 answer
  • Why is my family dissapointed in me?​
    7·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!