Which has higher percentage of oxygen: (Fe = 56, O = 16, C = 12) a) FeO b) FeCO3 c) Fe2O3 d) Fe3O4

Two students are given different samples of a substance and are instructed to determine the properties of the substance.Which st

musickatia [10]

Answer:

The boiling point of the substances

Explanation:

Because Boiling point is an intensive property.

5 0

3 years ago

The cylinder of aluminum in class was approximately 13mm in circumference and 42mm in length. What would be it's approximate mas

Roman55 [17]

Answer:

Mass, m = 1.51 grams

Explanation:

It is given that,

The circumference of Aluminium cylinder, C = 13 mm = 1.3 cm

Length of the cylinder, h = 4.2 cm

We know that the density of the Aluminium is 2.7 g/cm³

Circumference, C = 2πr

$r=\dfrac{C}{2\pi}\\\\r=\dfrac{1.3}{2\pi}\\\\r=0.206\ cm$

Density is equal to mass per unit volume.

$d=\dfrac{m}{V}$

m is mass of the cylinder

V is the volume of the cylinder

$V=\pi r^2h\\\\V=\dfrac{22}{7}\times0.206^2\times 4.2\\\\V=0.5601\ cm^3$

So,

$m=d\times V\\\\m=2.7\times 0.5601\\\\m=1.51\ g$

So, the mass of the cylinder is 1.51 grams.

5 0

3 years ago

Two substances, A and Z, are to be identified. Substance A can not be broken down by a chemical change. Substance Z can be broke

I am Lyosha [343]

The answer is 3). This is because elements are the simplest form of a substance, and cannot be broken down any further. Compounds on the other hand are much more complex than elements and can be broken down INTO elements. For example, Na, sodium, is an element and cannot be broken down further. H2O, water, is a compound and can be broken down into Hydrogen and Oxygen.

4 0

3 years ago

Select the compound with the lowest lattice energy.

tatyana61 [14]

Answer:

A. CsBr(s)

Explanation:

we will get here compound with the lowest lattice energy

solution

As we know that Lattice energy is always proportional to the charge of ions and it is inversely proportional to the size of ions.

so that by the smallest charge and the largest size give us the lowest lattice energy and that charge and size is express as here as

Charge

Cs (+1), K(+1), Na (+1), Cl(-1), Br(-1), Sr(+2), Ca(+2), O(-2) .......................1

and

Size

Na+ < Ca2+ < K+ < Sr2+ < Cs+, O2- < Cl- < Br- ..........................2

so that here

correct answer is A. CsBr

6 0

3 years ago

What volumes of 0.200 M HCOOH and 2.00 M NaOH would make 500. mL of a buffer with the same pH as one made from 475 mL of 0.200 M

Fed [463]

36 ml of NaOh and 464 ml of HCOOH would be enough to form 500 ml of a buffer with the same pH as the buffer made with benzoic acid and NaOH.

What is benzoic acid found in?

Some natural sources of benzoic acid include: Fruits: Apricots, prunes, berries, cranberries, peaches, kiwi, bananas, watermelon, pineapple, oranges.
Spices: Cinnamon, cloves, allspice, cayenne pepper, mustard seeds, thyme, turmeric, coriander.

Calculate the amount of moles in NaOH and benzoic acid. This calculation is done by multiplying molarity by volume.

Amount of moles of NaOH -2 × 0.025 = 0.05 mol

Amount of moles of benzoic acid 2 × 0.475 = 0.095 mol

In this case, we can calculate the pH produced by the buffer of these two reagents, as follows

$pH = pKa + log\frac{base}{acid}$