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3 years ago

How would you prepare 2.5 L of a 0.800M solution of KNO3?

1 answer:

7 0

First find the mass of solute:

Molar mass KNO₃ = 101.1032 g/mol

mass = Molarity * molar mass * volume

mass = 0.800 * 101.1032 * 2.5

mass = 202.2064 g of KNO₃

To prepare 2.5 L (0800 M) of KNO3 solution, must weigh 202.2064 g of salt, dissolve in a Beker, transfer with the help of a funnel of transfer to a volumetric flask, complete with water up to the mark, capping the balloon and finally shake the solution to mix.

hope this helps!

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Considering that the mantle is 44.8% oxygen and 21.5% silicon by mass, calculate the mole ratio of oxygen atoms to silicon atoms

horrorfan [7]

The mantle has a mass of around $4.278 X 10 ^2^4 kg$ that is around 68.4% of earth's mass.

So to calculate moles we need to first find out the mass of oxygen and silicon present in mantle. It is given that oxygen is 44.8% by mass in mantle and 21.5% by mass in mantle, therefore to calculate its mass, we need to use $\text{mass percentage }=\frac{\text{mole of solute}}{\text{mass of solution}}\times100$

Now, to calculate mass percentage of oxygen

$44.8 =\frac{x}{4.278X10^2^4kg}\times100$

$x= 191.65\times10^2^2kg$

Similarly the mass of silicon can be calculated

$21.5 =\frac{x}{4.278X10^2^4kg}\times100$

$x=91.977\times10^2^2kg$

Now, the moles of any substance is calculated by

$\text{moles}= \frac{\text{given mass}}{\text{molar mass}}$

$\text{moles of oxygen}= \frac{191.65\times10^2^2kg}{2.6566962\times10^-^2^6kg}$

where, mass of oxygen in kilograms is $2.6566962\times10^-^2^6kg$

So, $\text{moles of oxygen}=72.1384\times10^4^8\text{moles of O}$

Similarly $\text{moles of silicon}= \frac{91.977\times10^2^2kg}{4.663\times10^-^2^6kg}$

$\text{moles of silicon}=19.724\times10^4^8\text{moles of Si}$

Now, to calculate mole ratio we need to divide every moles to the lowest calculated mole that is the moles of Si and round it off to the nearest whole number.

$\text{mole ratio of oxygen}= \frac{72.138\times10^4^8kg}{19.724\times10^4^8kg}$

$=3.65\approx 4$

$\text{mole ratio of Silicon}=\frac{19.724\times10^4^8}{19.724\times10^4^8}$

$=1$

$\text{Mole ratio of Oxygen : Mole ratio of Silicon} = 4:1$

6 0

3 years ago

Read 2 more answers

2. Water is an excellent solvent. With water being a polar

ladessa [460]

Answer:

Water acts as a solvent of carbon dioxide excreted from tissues, in blood and helps in regulating pH (because it forms carbonic acid that lowers pH when it tends to get higher). Blood pH should be maintained at about 7.4. One major reason is that the structure of protein is dependent ton pH because pH determines its ionization hence also affecting the charges and interaction between side groups of amino acids. A change in pH may, therefore, denature proteins and negatively affect cellular functions.

Explanation:

To get more on how water acts as a universal solvent check out brainly.com/question/7007192

7 0

2 years ago

Balancing Practice (some of these may be in the simulation)

agasfer [191]

Answer:

see below

Explanation:

16. 1 P₄(s) + 6 F₂(g) → 1 PF₃(s)

17. 2 C(s) + 2 H₂O(g) → 1 CH₄(g) + 1 CO₂(g)

18. 2 HgO(s)→ 1 O₂(g) + 2 Hg(l)

19. 1 CaCO₃(s) → 1 CO₂(g) + 1 CaO(s)

8 0

3 years ago

Identify the type of interactions involved in each of the following processes taking place during the dissolution of sodium chlo

icang [17]

Answer:

A. Interactions between the ions of sodium chloride (solute-solute interactions).

B. Interactions involving dipole-dipole attractions (solvent-solvent interactions).

C. Interactions formed during hydration (solute-solvent interactions).

D. Interactions involving ion-ion attractions (solute-solute interactions).

E. Interactions associated with an exothermic process during the dissolution of sodium chloride (solute-solvent interactions).

F. Interactions between the water molecules (solvent-solvent interactions).

G. Interactions formed between the sodium ions and the oxygen atoms of water molecules (solute-solvent interactions).

Explanation:

The solution process takes place in three distinct steps:

Step 1 is the separation of solvent molecules.

Step 2 entails the separation of solute molecules.

These steps require energy input to break attractive intermolecular forces; therefore, they are endothermic.

Step 3 refers to the mixing of solvent and solute molecules. This process can be exothermic or endothermic.

If the solute-solvent attraction is stronger than the solvent-solvent attraction and solute-solute attraction, the solution process is favorable, or exothermic (ΔHsoln < 0). If the solute-solvent interaction is weaker than the solvent-solvent and solute-solute interactions, then the solution process is endothermic (ΔHsoln > 0).

In the dissolution of sodium chloride, this process is exothermic.

3 0

3 years ago

A chemical buffer is a solution that increases pH changes when small quantities of an acid or base are added. True False

Alex

Answer:

false

Explanation:

A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is added to it. A buffer protects from ph increasing.

7 0

2 years ago