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xeze [42]
3 years ago
8

During an experiment, iron powder and sulfur powder were heated together to form a black mass. It was observed that a magnet, wh

en brought near the black mass, did not attract the black mass. Which of the following correctly justifies the observation?
A. The black mass is a mixture and no longer retains the properties of iron.
B. The black mass is a mixture and retains the properties of iron.
C.The black mass is a pure substance and no longer retains the properties of iron.
D. The black mass is a pure substance and retains the properties of iron.
Chemistry
1 answer:
Readme [11.4K]3 years ago
3 0

Answer:The correct answer is option(C).

Explanation:

Compound is a substance made up of two or more elements which are chemically joined together.

When the iron and sulfur heated together in the test tube a chemical reaction reaction took place between the iron and sulfur which lead to the formation of iron sulfur compound (here black mass).And this compound will differ in chemical proprieties with respect to its constituting pure element.

When the magnet was brought near to it , it doesn't attracted the black mass towards itself.This is because the 'The black mass is a compound and no longer retains the properties of iron'.

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Please help im so bad at science
igomit [66]

a.bond energy

c. endothermic reaction

d. exothermic reaction

f.exothermic

g.endothermic

4 0
3 years ago
A 1.268 g sample of a metal carbonate, MCO₃, was treated 100.00 mL of 0.1083 M H₂SO₄, yielding CO₂ gas and an aqueous solution o
attashe74 [19]

Answer:

MCO3 is BaCO3

The mass of CO2 produced is 0.28g of CO2

Explanation:

The first step in solving the question is to put down the balanced reaction equations as shown in the image attached. Secondly, we obtain the relative number of moles acid and base as mentioned in the question. The balanced neutralization reaction equation is used to obtain the number of moles of excess acid involved in the neutralization reaction.

This is then subtracted from the total number of moles acid to give the number of moles of acid that reacted with MCO3. From here, the molar mass of MCO3 and identity of M can be found. Hence the mass of CO2 produced is calculated as shown.

6 0
3 years ago
Which of the following is correct concerning Hess's law?
Margaret [11]
I believe the correct answer would be that t<span>he change in enthalpy can be found by adding the enthalpies of the individual thermochemical reactions of a chemical reaction.</span> In Hess' Law, enthalpy is independent of the mechanism of the reaction. The enthalpy should be the sum of all the changes in the reaction.
3 0
3 years ago
Read 2 more answers
The Ka of hydrazoic acid (HN3) is 1.9 × 10-5 at 25.0 °C. What is the pH of a 0.40 M aqueous solution of HN3?
siniylev [52]

Answer:

The pH of the solution is 2.56.

Explanation:

Given :

Concentration (c) = 0.40 M

Acid dissociation constant = K_a=1.9\times 10^{-5}

The equilibrium reaction for dissociation of HN_3 (weak acid) is,

                           HN_3+H_2O\rightleftharpoons N_3^{-}+H_3O^+

initially conc.         c                       0         0

At eqm.              c(1-\alpha)                c\alpha        c\alpha

Dissociation constant is given as:

K_a=\frac{(c\alpha)(c\alpha)}{c(1-\alpha)}

1.9\times 10^{-5}=\frac{(0.40\alpha)(0.40\alpha)}{0.40(1-\alpha)}

By solving the terms, we get value of (\alpha)}

\alpha=0.00686832

No we have to calculate the concentration of hydronium ion or hydrogen ion.

[H^+]=c\alpha=0.4\times 0.00686832=0.002747 M

Now we have to calculate the pH.

pH=-\log [H^+]

pH=-\log (0.002747)

pH=2.56

Therefore, the pH of the solution is, 2.56.

8 0
3 years ago
Guys please help me...
valentina_108 [34]

Answer:

On the farm there are 70 chickens.

Explanation:

We can directly <u>work out the number of ducks from the given number of pigs</u>, with the <em>ratio of ducks to pigs</em>:

  • 36 pigs * \frac{5Ducks}{9Pigs} = 20 ducks

Then we<u> work out the number of chickens</u>, using the ration of chickens to ducks:

  • 20 ducks * \frac{7Chickens}{2Ducks} = 70 chickens

If on the farm there are 36 pigs, there are 70 chickens as well.

7 0
3 years ago
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