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4 years ago

Which of the following statements is true?

1 answer:

7 0

A is automatically wrong since protons have a +1 charge. B is wrong since it states electrons have no charge. C is wrong since it says electrons have no charge. Therefore we are left with D.

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You need to make 500 mL of a 3.40 M solution of sodium chloride. The only available solution is 1.5 M. Determine how to make the

vlabodo [156]

Answer: (1.5 M) V1 = (3.40 M) (500mL)

(multiply 3.40M x 500mL) V1 = 1700 mL

1700 mL of the 1.5 M NaCl + 1200mL of water.

Explanation:

3 0

3 years ago

Find the mass of sucrose (molecular mass=342) required to be dissolved per 600cm² solution to prepare a semi molar solution.

Natalka [10]

Answer:

102.6 g

Explanation:

Firstly, let's understand the terms used in the question. Semi-molar solution is a solution which has a molarity of:

$c=\frac{1}{2} M=0.5 M$

We're given the molar mass of:

$M=342 \frac{g}{mol}$

Let's use the definition of molarity: molarity is the ratio between the moles of solute and the volume of solution:

$c=\frac{n}{V}$

From here, we wish to express moles, n, as the ratio of mass of sucrose to its molar mass:

$n=\frac{m}{M}$

Substitute it back into the equation of molarity:

$c=\frac{n}{V}=\frac{\frac{m}{M} }{V}=\frac{m}{MV}$

Since we wish to find mass, let's multiply both sides of the equation by MV to obtain mass equation:

$m=cMV$

Now, convert volume into liters knowing that 1 mL = 1 cm³ and 1000 mL = 1 L:

$600 cm^3 \cdot\frac{1 mL}{1 cm^3} \cdot \frac{1 L}{1000 mL} =0.600 L$

Substitute all three variables into the equation:

$m=0.5 M\cdot342 \frac{g}{mol}\cdot0.600 L=102.6 g$

4 0

3 years ago

All of the statements are true about the arrangement of elements in the periodic table EXCEPT that the

LUCKY_DIMON [66]

Answer: C) rare earth elements are in the first column, on the left.

Explanation:

In fact, rare earth elements are in the third column, on the left.

The periodic table of the elements is an arrangement of the chemical elements in the form of a table, ordered by their atomic number (number of protons), by their configuration of electrons and their chemical properties. It was progressively developed over time as the scientific knowledge advanced; for this reason many modifications and corrections might be done in the future.

This table is divided into rows and columns, which represent the periods and groups or families. For its location the atomic number and valence of each element was considered.

In this sense, the elements in the periodic table are mainly arranged as follows:

-Alkali metals and Alkaline Earth metals in the first two columns, on the left.

-Rare earth elements in the third column (rows 6 and 7), on the left.

-Transition metals in the center.

-Basic metals and semi-metals to the right

-Non-metals to the right (and Hidrogen in the first row and column)

-Noble gases (or inert gases) farthest to the right.

3 0

3 years ago

Read 2 more answers

Given the following chemical equation, if 50.1 grams of silicon dioxide is heated with excess carbon and 32.3 grams of silicon c

aivan3 [116]

Answer:

97%.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

SiO2 (s) + 3C (s) —> SiC(s) + 2CO(g)

Next, we shall determine the mass of SO2 that reacted and the mass of SiC produced from the balanced equation. This is illustrated below:

Molar mass of SiO2 = 28 + (16x2) = 60 g/mol

Mass of SO2 from the balanced equation = 1 x 60 = 60 g

Molar mass of SiC = 28 + 12 = 40 g/mol

Mass of SiC from the balanced equation = 1 x 40 = 40 g.

From the balanced equation above,

60 g of SiO2 reacted to produce 40 g of SiC.

Next, we shall determine the theoretical yield of SiC. This can be obtained as follow:

From the balanced equation above,

60 g of SiO2 reacted to produce 40 g of SiC.

Therefore, 50.1 g of SiO2 will react to produce = (50.1 x 40)/60 = 33.4 g of SiC.

Therefore, the theoretical yield of SiC is 33.4 g

Finally, we shall determine the percentage yield of SiC as follow:

Actual yield of SiC = 32.3 g

Theoretical yield of SiC = 33.4 g

Percentage yield =?

Percentage yield = Actual yield /Theoretical yield x 100

Percentage yield = 32.3/33.4 x 100

Percentage yield = 96.7 ≈ 97%

Therefore, the percentage yield of the reaction is 97%.

3 0

3 years ago

A solution contains 2 meq/ml of kcl. if a 20 ml ampule of this solution is diluted to 1 liter what is the percent strength of th

Serjik [45]

We are given that the concentration of the KCl is 2 meq / mL. Assuming that the ampule also has exactly this concentration, therefore:

amount of KCl in ampule = (2 meq / mL) * (20 mL)

amount of KCl in ampule = 40 meq

This amount of KCl is now inside a solution of 1 Liter (also equivalent to 1000 mL), therefore the new concentration in the resulting solution is:

new concentration = 40 meq / 1000 mL

new concentration = 0.04 meq / mL

Since 0.04 in decimal is 4% in percentage, therefore the strength of the resulting solution is 4% KCl.

7 0

3 years ago