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GarryVolchara [31]
3 years ago
9

A 780.0 g hard-water sample contains 276 mg Ca. What is the concentration in parts per million?

Chemistry
1 answer:
valentina_108 [34]3 years ago
5 0

Answer:

353 ppm

Explanation:

PPM also refers to parts per million, it represents a low concentration of a solution. It represents 0.001 gram or a milligram in 1000 mL, equivalent to 1 mg per liter

Given that;

276 mg of Ca in 780.0 g of water

1 ppm = 1 mg/L

780 g = 780 mL = 0.78 L

Therefore;

= 276 mg/ 0.78 L  

=  353.84mg/L

= 353 ppm

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Calculate the chemical amount of ammonia present in a 11.22g sample of the compound​
11Alexandr11 [23.1K]

Answer:

3.97 x 10²³atoms

Explanation:

Given parameters:

Mass of ammonia = 11.22g

Unknown:

Chemical amount of ammonia present  = ?

Solution:

The chemical amount present in a substance is the number of atoms it contains.

To solve this problem, from the given mass find the number of moles first.

  Number of moles  = \frac{mass}{molar mass}

Molar mass of NH₃   = 14 + 3(1) = 17g/mol

  Number of moles  = \frac{11.22}{17}   = 0.66mole

   1 mole of any substance contains  6.02 x 10²³ atoms

  0.66 mole of ammonia will contain 0.66 x 6.02 x 10²³ atoms

                                                            = 3.97 x 10²³atoms

6 0
3 years ago
Mendeleev created the first periodic table by arranging the elements in the order of ?
Maslowich
Mendleev arranged his periodic table in order of Atomic Mass...
4 0
4 years ago
Which atom is oxidized in the reaction of benzhydrol with bleach?
77julia77 [94]

Answer:

Which atom is oxidized in the reaction of benzhydrol with bleach?

Explanation:

n this experiment, students will perform a simple oxidation reaction of a secondary

alcohol. Recall that Oxidation Is a Loss of electrons while Reduction Is a Gain of electrons (OIL

RIG). In order to apply this mnemonic, you must know the oxidation states of each atom within

the compound, with particular interest on carbon. Carbon can carry oxidation states ranging

from -4 to +4. A few examples are shown in Figure 1 below. It is also common for carbon to

carry an oxidation state of -3, -1, +1, and +3.

Figure 1. Examples of carbon’s oxidation levels.

You may have noticed that all of the compounds in Figure 1 are neutral and carbon has

zero formal charge in each example. The concept of oxidation state and formal charge are

similar with one important difference in the calculation. Both are calculated by taking the

difference between the valence electrons (from the periodic table) and the number of electrons

belonging to that atom within the molecule. For a given atom, the valence electrons will never

change but the electrons ‘belonging’ the atom in the molecule will vary depending on number of

lone pairs and attachments to more or less electronegative atoms. The important difference in

the calculation of oxidation states and formal charge is based on the following assignment of

bonding electrons (Figure 2). This is how the highlighted carbon in ethanol can have an

oxidation state of -1 but a formal charge of zero.

- Oxidation states assign bonding electrons to the more electronegative atom in a bond,

except when the two atoms are the same and the bonding electrons are split equally.

7 0
3 years ago
Read 2 more answers
A generic solid, X, has a molar mass of 78.2 g/mol. In a constant-pressure calorimeter, 12.6 g of X is dissolved in 337 g of wat
MissTica

Answer:

a) Q = 2047.8 J (ΔH is negative because it's an exothermic reaction)

b) ΔH = -12.7 kJ /mol

Explanation:

Step 1: Data given

Molar mass of X = 78.2 g/mol

In a constant-pressure calorimeter, 12.6 g of X is dissolved in 337 g of water at 23.00 °C.

The temperature rise to 24.40 °C

The specific heat of the solution = 4.184 J/g°C

Step 2: Calculate the total mass

Total mass of the solution is given by  

Total mass = 12.6 grams + 337 grams = 349.6 grams

Step 3: Calculate heat

Q = m*c*ΔT

⇒ m = the total mass = 349.6 grams

⇒ c = the specific heat of solution = 4.184 J/g°C

⇒ ΔT = The change of temperature = T2 - T1 = 24.40 - 23.00 = 1.40 °C

Q = 2047.8 J (ΔH is negative because it's an exothermic reaction)

What is the enthalpy of the reaction?

Calculate number of moles = mass/ molar mass

Moles X = 12.6 grams / 78.2 g/mol

Moles X = 0.161 moles

ΔH = -2047.8 J / 0.161 moles

ΔH = -12719.3 J/mol = -12.7 kJ /mol

8 0
3 years ago
How many protons and neutrons are there in an atom of boron11?
Komok [63]
5 protons and six neutrons
6 0
3 years ago
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