Question

which chemical reactions are not possible according to daltons atomic theory? (square) (ce{ccl4 -> ch4}) (square) (ce{n2 + 3 h2 -> 2 nh3}) (square) (ce{2 h2 + o2 -> 2 h2o + au})

Explanation:

Step1: Recall Dalton's Atomic Theory

Dalton's atomic theory states that atoms are neither created nor destroyed in a chemical reaction, and atoms of one element cannot change into atoms of another element. So, in a chemical reaction, the elements present in the reactants must be the same as those in the products.

Step2: Analyze each reaction

• For $\ce{CCl4 -> CH4}$: Reactant has C and Cl, product has C and H. Cl is replaced by H, which would mean atoms of Cl changed to H (different elements), violating Dalton's theory. But wait, actually, this reaction as written is not a simple rearrangement—wait, no, let's check the third reaction first. Wait, no, let's check each:
• Reaction 1: $\ce{CCl4 -> CH4}$: Reactants have C, Cl; products have C, H. So Cl atoms would have to turn into H atoms (different element), which is not allowed. But also, reaction 3: $\ce{2H2 + O2 -> 2H2O + Au}$: Reactants have H and O; product has H, O, and Au. Au is a new element not in reactants, so atoms of Au would have to be created, violating the theory. Wait, but let's re - evaluate:

Dalton's theory: Atoms are indestructible and retain their identity in reactions (no transmutation, and elements in reactants = elements in products).

• Reaction 1: $\ce{CCl4 -> CH4}$: Reactants: C, Cl; Products: C, H. So Cl (reactant) is not in product, H (product) not in reactant. So this reaction would require Cl atoms to disappear and H atoms to appear, which is not allowed.
• Reaction 2: $\ce{N2 + 3H2 -> 2NH3}$: Reactants: N, H; Products: N, H. This is a valid reaction (synthesis of ammonia), elements are conserved.
• Reaction 3: $\ce{2H2 + O2 -> 2H2O + Au}$: Reactants: H, O; Products: H, O, Au. Au is not in reactants, so this reaction would create Au atoms, which is not allowed by Dalton's theory (atoms are not created, and elements in reactants must match products). Also, reaction 1: $\ce{CCl4 -> CH4}$: Cl is in reactant, not product; H in product, not reactant. So both reaction 1 and 3? Wait, but let's check the original problem. Wait, maybe I made a mistake. Wait, $\ce{CCl4 -> CH4}$: Is this a possible reaction? No, because to get CH4 from CCl4, you would need to replace Cl with H, but according to Dalton, atoms of Cl can't become H. And $\ce{2H2 + O2 -> 2H2O + Au}$: Au is not in reactants, so it can't appear in products. The reaction $\ce{N2 + 3H2 -> 2NH3}$ is a valid reaction (Haber process - type, and elements are conserved). So the reactions that are not possible are $\ce{CCl4 -> CH4}$ and $\ce{2H2 + O2 -> 2H2O + Au}$. But let's confirm:

Dalton's postulates:

1. All matter is made of atoms. Atoms are indivisible and indestructible.
2. All atoms of a given element are identical in mass and properties.
3. Compounds are formed by a combination of two or more different kinds of atoms.
4. A chemical reaction is a rearrangement of atoms.

So in a chemical reaction, the atoms are rearranged, but the same atoms (same elements) must be present in reactants and products.

• $\ce{CCl4 -> CH4}$: Reactants have C, Cl; products have C, H. So Cl atoms are not in products, H atoms not in reactants. So this is not a rearrangement of the same atoms (since Cl and H are different), so not possible.
• $\ce{2H2 + O2 -> 2H2O + Au}$: Reactants have H, O; products have H, O, Au. Au is a new element, so atoms of Au are created, which violates the indestructible/unchangeable nature (and also, they weren't in reactants). So this is not possible.
• $\ce{N2 + 3H2 -> 2NH3}$: Reactants N, H; products N, H. Atoms are rearranged (N2 and H2 molecules break, N and H atoms combine to form NH3),…

Answer:

The reactions that are not possible are $\boldsymbol{\ce{CCl4 -> CH4}}$ and $\boldsymbol{\ce{2H2 + O2 -> 2H2O + Au}}$. So the checkboxes for $\ce{CCl4 -> CH4}$ and $\ce{2H2 + O2 -> 2H2O + Au}$ should be selected.